Methods and systems of converting metal-ion containing solids for carbon dioxide capture and storage

Abstract

Systems and methods of converting metal-ion containing solids for carbon dioxide capture and storage are disclosed. In some embodiments, the described systems and methods integrate all of the steps necessary for carbon capture and storage into a single chamber reactor. In some example embodiments, the reactor comprises two chambers. In some embodiments, the reactor comprises three chambers. The systems and methods may produce metal carbonates, and in some embodiments, additionally produce silica.

Description

METHODS AND SYSTEMS OF CONVERTING METAL-ION CONTAINING SOLIDS FOR CARBON DIOXIDE CAPTURE AND STORAGECross-Reference to Related Applications

[0001] This application claims priority from US application No. 63 / 558,834 filed28 February 2024 and entitled METHODS AND APPARATUS FOR CONVERTING MINERALS TO METAL CARBONATES and US application No. 63 / 699,988 filed27 September 2024 and entitled METHODS AND APPARATUS FOR ELECTROLYSIS OF SULFUR SPECIES AND CARBON DIOXIDE CAPTURE AND STORAGE, both of which are hereby incorporated herein by reference for all purposes. For purposes of the United States of America, this application claims the benefit under 35 U.S.C. §119 of US application No. 63 / 558,834 filed28 February 2024 and entitled METHODS AND APPARATUS FOR CONVERTING MINERALS TO METAL CARBONATES and US application No. 63 / 699,988 filed 27 September 2024 and entitled METHODS AND APPARATUS FOR ELECTROLYSIS OF SULFUR SPECIES AND CARBON DIOXIDE CAPTURE AND STORAGE which are hereby incorporated herein by reference for all purposes.Field

[0002] The invention pertains to methods and systems of producing metal carbonates from metal-ion containing solids, in particular, for carbon dioxide capture and storage.Background

[0003] Rock weathering involves the mineralization of CO2 into inert solid carbonates, and has the potential to store approximately 105gigatons of CO2. This process is initiated by the reaction of water with CO2 to generate carbonic acid (H2CO3). The H2CO3 can then dissociate into CO32-and H+. This acid then reacts with silicate rocks such as forsterite (Mg2SiO4) or wollastonite (CaSiOs) to form SiO2 and M2+(M2+= Mg2+or Ca2+). These liberated M2+ions can then react with COs2-to form solid mineral carbonates. The reactions associated with the rock weathering of calcium silicates are listed in equations (1) to (4), equation (5) is the overall equation for rock weathering.Carbon capture (slow): CC>2(g) + H2OQ H2CC>3(aq) (1)Carbonic acid dissociation H2CO3(aq) 2H+(aq) + CO32'(aq) (2)(thermodynamically unfavored):Silicate dissolution: CaSiO3(s) + 2H+(aq) —> Ca2+(aq) + H2OQ + (3)SiO2(S)Mineralization: Ca2+(aq) + CO32'(aq) CaCO3(S) (4)Rock weathering (slow): CO2(g) + CaSiO3(s) —> CaCOs + SiO2(S) (5)

[0004] Rock weathering could store gigatons of CO2 per year, but the weathering of silicates is slow due to the weakly acidic nature of H2CO3. Consequently, merely 0.13 gigatons of CO2 from the atmosphere per year is stored from natural weathering processes. The rate of mineralization can be increased by heating Mg-rich silicates into more reactive Mg species such as MgO and Mg(OH)2. However, the high temperatures required to heat the Mg-rich silicates drive the cost to over $200 USD per tonne of sequestered CO2, which is not compatible with the need to store carbon at a cost of less than $100 USD per tonne of sequestered CO2.

[0005] The inventors have recognised a general need for improved systems and methods to convert metal-ion containing solids for capturing and permanently storing carbon dioxide efficiently and cost-effectively. In some embodiments, the metal-ion containing solids are converted to metal carbonates and in embodiments in which the metal-ion containing solids comprise a silicate containing mineral, silica is additionally produced.Summary

[0006] This application has a number of aspects. These include, without limitation:• systems and methods of producing metal carbonates from metal-ion containing solids;• systems and methods for producing silica from metal-ion containing solids which comprise a silicate containing mineral;• systems and methods for performing carbon dioxide capture and mineralization which integrates all of the steps necessary for carbon dioxide capture and storage in a single electrochemical cell without the need for additional downstream reactors;• systems and methods which integrate the oxidation of sulfur species in producing metal carbonates and / silica from metal-ion containing solids;• systems and methods which couple the capture and mineralization of carbon dioxide gas with the oxidation of sulfurous waste;• systems and methods of converting useful products comprising sulfur from sulfur-containing species having a sulfur atom in a lower oxidation state such as sulfur species that may be found in waste streams;• systems and methods of producing sulfuric acid from sulfur-containing species having a sulfur atom in a lower oxidation state such as sulfur species that may be found in waste streams;• systems and methods for continuous conversion of metal ion-containing solids for carbon dioxide capture and storage.

[0007] One aspect of the invention pertains to systems and methods for converting metal-ion containing solids for carbon dioxide capture and storage using a two- chamber electrochemical cell. The systems and methods may produce metal carbonates and in some embodiments, additionally produce silica using a two- chamber electrochemical cell.

[0008] In some embodiments, the method comprises applying an electrical potential between an anode and a cathode of an electrochemical cell. The electrochemical cell comprises an anode chamber, a cathode chamber, and a separator separating the anode chamber and the cathode chamber. The method comprises oxidizing a first hydrogen-containing reactant, at the anode, to form hydrogen ions, and reducing a second hydrogen-containing reactant, at the cathode, to form hydroxide ions. A feedstock comprising a metal-ion containing solid is supplied to the anode chamber. The metal-ion containing solid react with the hydrogen ions formed at the anode to yield metal ions and / or silica. The metal ions are permeated through the separator from the anode chamber to the cathode chamber. A carbon dioxide feedstock is supplied to the cathode chamber. The hydroxide ions formed at the cathode reactwith the carbon dioxide feedstock and the metal ions to yield metal carbonate in the cathode chamber.

[0009] One aspect of the invention relates to a carbon dioxide capture and storage system. The carbon dioxide capture and storage system comprises a source of carbon dioxide feedstock and an electrochemical reactor. The electrochemical reactor comprises an anode exposed to an anode chamber, adapted to oxidize a first hydrogen-containing reactant to form hydrogen ions, a cathode exposed to a cathode chamber, adapted to reduce a second hydrogen-containing reactant to form hydroxide ions, and a separator separating the anode chamber and the cathode chamber. A power supply is connected to apply a potential difference between the anode and the cathode. An inlet is provided at the cathode chamber. The inlet may be fluidly connected to an outlet of the source of a carbon dioxide feedstock configured to supply the carbon dioxide feedstock from the source into the cathode chamber. An inlet is provided at the anode chamber. The inlet may be connected to receive a supply of metal-ion containing solids into the anode chamber, within which the metalion containing solids are caused to react with the hydrogen ions formed at the anode to produce metal ions and / or silica. The metal ions are permeated into the cathode chamber to react with the carbon dioxide feedstock to yield metal carbonate.

[0007] One aspect of the invention pertains to systems and methods for converting metal-ion containing solids for carbon dioxide capture and storage which integrate the oxidation of a sulfur-containing species. The systems and methods may produce metal carbonates and in some embodiments, additionally produce silica. The method comprises applying an electrical potential between an anode and a cathode of an electrochemical cell, wherein the electrochemical cell comprises an anode chamber, a cathode chamber, and a separator separating the anode chamber and the cathode chamber. A sulfur-containing species with a sulfur atom in a lower oxidation state contained in a first hydrogen-containing reactant is oxidized at the anode to form a sulfur-containing species with a sulfur atom in a higher oxidation state and hydrogen ions. A second hydrogen-containing reactant is reduced at the cathode to form hydroxide ions. A feedstock comprising a metal-ion containing solid is supplied to the anode chamber. The metal-ion containing solid reacts with the hydrogen ions formed at the anode to yield metal-ions and / or silica.

[0008] In some embodiments, the method further comprises supplying a feedstock comprising metal ions to the cathode chamber, and supplying a carbon dioxide feedstock to the cathode chamber. The hydroxide ions formed at the cathode may react with the carbon dioxide feedstock and the metal ions to yield metal carbonate.

[0012] In some embodiments, a solution is removed from the anode chamber. The solution may comprise the metal ions. In such embodiments, the method further comprises supplying the solution comprising the metal ions to the cathode chamber, causing the metal ions to react with the hydroxide ions formed at the cathode with the carbon dioxide feedstock to yield metal carbonate.

[0013] In some embodiments, the metal ions of the metal-ion containing solids permeate through the separator from the anode chamber to the cathode chamber for reacting with the hydroxide ions formed at the cathode with the carbon dioxide feedstock to yield the metal carbonate.

[0014] One aspect of the invention pertains to a carbon dioxide capture and storage system which integrates the oxidation of a sulfur containing species. The system may comprise a source of carbon dioxide feedstock, a reservoir, and an electrochemical reactor. The electrochemical reactor comprises an anode exposed to an anode chamber, adapted to oxidize a sulfur-containing species with a sulfur atom in a lower oxidation state contained in a first hydrogen-containing reactant to form a sulfur- containing species with a sulfur atom in a higher oxidation state and hydrogen ions, a cathode exposed to a cathode chamber, adapted to reduce a second hydrogencontaining reactant to form hydroxide ions, and a separator separating the anode chamber and the cathode chamber. A power supply is connected to apply a potential difference between the anode and the cathode. An inlet is arranged at the anode chamber connected to receive a supply of metal-ion containing solids into the anode chamber, within which the metal-ion containing solids are caused to react with the hydrogen ions formed at the anode to produce metal ions and / or silica. An outlet is arranged at the anode chamber fluidly connected to an inlet of the reservoir arranged for output of the metal ions formed at the anode chamber. A second inlet is arranged at the cathode chamber fluidly connected to an outlet of the reservoir arranged for input of the metal ions into the cathode chamber for reacting with the carbon dioxide feedstock to yield metal carbonate.

[0015] One aspect of the invention pertains to systems and methods for converting metal-ion containing solids for carbon dioxide capture and storage using a three- chamber electrochemical cell. The systems and methods produce metal carbonates and in some embodiments, for additionally produce silica. In some embodiments, the method comprises applying an electrical potential between an anode and a cathode of an electrochemical cell, wherein the electrochemical cell comprises an anode chamber, a cathode chamber, a chemical chamber, a bipolar membrane separating the anode chamber and the chemical chamber, and a separator separating the chemical chamber and the cathode chamber. Water is electrochemically dissociated at the bipolar membrane water into hydrogen ions and hydroxide ions. An oxidation reactant is oxidized at the anode to form an oxidation product. A hydrogen-containing reactant is reduced at the cathode to form hydroxide ions. A feedstock comprising metal-ion containing solids is supplied to the chemical chamber. The metal-ion containing solids react with the hydrogen ions formed at the bipolar membrane to yield metal ions and / or silica. The metal ions may be permeated through the separator from the chemical chamber to the cathode chamber. A carbon dioxide feedstock is supplied to the cathode chamber. The hydroxide ions formed at the cathode may react with the carbon dioxide feedstock and the metal ions to yield metal carbonate.

[0009] One aspect of the invention pertains to a carbon dioxide capture and storage system which comprises a source of a carbon dioxide feedstock and an electrochemical reactor. The electrochemical reactor comprises an anode exposed to an anode chamber, adapted to oxidize an oxidation reactant to form an oxidation product, a cathode exposed to a cathode chamber, adapted to reduce a hydrogencontaining reactant to form hydroxide ions, a chemical chamber arranged between the anode chamber and the cathode chamber, a bipolar membrane separating the anode chamber and the chemical chamber, the bipolar membrane being adapted to electrochemically dissociate water into hydrogen ions and hydroxide ions, and a separator separating the chemical chamber and the cathode chamber. A power supply is connected to apply a potential difference between the anode and the cathode. An inlet may be provided at the cathode chamber. The inlet may be fluidly connected to an outlet of the source of the carbon dioxide feedstock configured tosupply the carbon dioxide feedstock from the source into the cathode chamber. An inlet may be provided at the chemical chamber. The inlet may be connected to receive a supply of metal-ion containing solids into the chemical chamber, within which the metal-ion containing solids are caused to react with the hydrogen ions formed at the bipolar membrane to produce metal ions and / or silica. The metal ions are permeated into the cathode chamber to react with the carbon dioxide feedstock to yield metal carbonate.

[0010] One aspect of the invention pertains to a method of producing a sulfur- containing species with a sulfur atom in a higher oxidation state. The method comprises applying an electrical potential between an anode and a cathode of an electrochemical cell, wherein the electrochemical cell comprises an anode chamber, a cathode chamber, and a separator separating the anode chamber and the cathode chamber. A sulfur-containing species with a sulfur atom in a lower oxidation state contained in a first hydrogen-containing reactant is oxidized at the anode to form a sulfur-containing species with the sulfur atom in a higher oxidation state and hydrogen ions. A reduction reactant is reduced at the cathode to form a reduction product.

[0011] One aspect of the invention pertain to methods of continuously converting metal-ion containing solids. In some embodiments, the method comprises applying an electrical potential between an anode and a cathode of an electrochemical cell, wherein the electrochemical cell comprises an anode chamber, a cathode chamber, and a separator separating the anode chamber and the cathode chamber. An oxidation reactant is oxidized at the anode to form an oxidation product. A reduction reactant is reduced at the cathode to form a reduction product. Electrolyte is caused to flow from the electrochemical cell to a solid-liquid extractor comprising the metalion containing solids. The metal ions from the metal-ion containing solids may be extracted in the solid-liquid extractor, thereby forming a metal-ion-enriched electrolyte comprising the metal ions. The metal-ion-enriched electrolyte from the solid-liquid extractor is caused to flow into the electrochemical cell. The metal ions are permeated to the cathode chamber. The metal ions and / or the hydroxide ions formed at the cathode are removed from the cathode chamber.

[0012] In some embodiments, the flowing of the metal ions and / or hydroxide ions outof the cathode chamber comprises flowing a mixture comprising the metal ions, hydroxide ions and an electrolyte out of the cathode chamber. In some embodiments, the mixture is supplied to a carbon capture and storage unit. A carbon dioxide feedstock may be supplied into the carbon capture and storage unit. The metal ions, hydroxide ions and the carbon dioxide feedstock may react in the carbon capture and storage unit to yield metal carbonates.

[0013] In some embodiments, the method further comprises separating, in the carbon capture and storage unit the metal carbonates from the mixture comprising the electrolyte. The separated electrolyte may be recycled to the electrochemical cell.

[0014] In some embodiments, the electrochemical cell additionally comprises a chemical chamber and a bipolar membrane separating the anode chamber and the chemical chamber, and wherein the separator is positioned between the chemical chamber and the cathode chamber. In such embodiments, the method further comprises electrochemically dissociating water, within the bipolar membrane, into hydrogen ions and hydroxide ions.

[0015] One aspect of the invention pertain to systems of continuously converting metal-ion containing solids. In some embodiments, the system comprises an electrochemical cell and a solid-liquid extractor. The electrochemical cell comprises an anode exposed in an anode chamber, adapted to oxidize an oxidation reactant to form an oxidation product, a cathode exposed in a cathode chamber, adapted to reduce a reduction reactant to form hydroxide ions, and a separator separating the anode chamber and the cathode chamber. The solid-liquid extractor is adapted to extract metal ions from the metal-ion containing solids, thereby forming a metal-ion- enriched electrolyte comprising the metal ions. In some embodiments, the solid-liquid extractor comprises an extractor inlet flowingly connected to a first outlet of the electrochemical cell, for flowing an electrolyte from the electrochemical cell to the solid-liquid extractor, and an extractor outlet flowingly connected to a cell inlet, for flowing the metal-ion-enriched electrolyte into the electrochemical cell so that the metal ions in the metal-ion-enriched electrolyte permeate through the separator to the cathode chamber. The electrochemical cell comprises a second outlet for flowing the metal ions and / or hydroxide ions formed at the cathode out of the cathode chamber.

[0016] In some embodiments, the system further comprises a carbon capture andstorage unit. The carbon capture storage unit comprises an inlet fluidly connected to the second outlet of the electrochemical cell for receiving a flow of the metal ions and / or hydroxide ions from the cathode chamber, and an outlet fluidly connected to a second cell inlet for flowing a supply of separated electrolyte into the electrochemical cell. The system may additionally comprise a source of carbon dioxide feedstock comprising an inlet flowingly connected to an inlet of the carbon capture and storage unit, for flowing a supply of carbon dioxide feedstock into the carbon capture and storage unit for bringing the metal ions, the hydroxide ions and the carbon dioxide feedstock into contact in the carbon capture and storage unit for reaction to yield metal carbonates.

[0017] In some embodiments, the system further comprises a chemical chamber between the anode chamber and the cathode chamber, and a bipolar membrane separating the chemical chamber and the anode chamber, the bipolar membrane being adapted to electrochemically dissociate water into hydrogen ions and hydroxide ions, and wherein the separator separates the chemical chamber and the cathode chamber.

[0018] Aspects of the invention relate to combining the described methods and apparatuses for converting metal-ion containing solids with downstream methods and apparatuses for making useful products. In some example embodiments, the one or more downstream methods and apparatuses may be configured to process the produced metal carbonates and / or produced silica to yield one or more additional useful products.

[0019] Non-limiting example uses of the metal carbonates produced by the described methods and systems include in paper, plastics, rubber coatings, pharmaceuticals or cement production. In some example embodiments, the metal carbonates comprise calcium carbonates or magnesium carbonates.

[0020] Non-limiting example uses of the silicon dioxide (SiC>2) or silica produced by the described methods and systems include glass manufacturing, chip manufacturing, silicon manufacturing, rubber manufacturing, catalyst supports, and optical fiber manufacturing.

[0021] In some embodiments, one or both oxygen gas and hydrogen gas is produced as gaseous byproducts from an oxidation reaction at the anode and reductionreaction at the cathode respectively. In some embodiments, one or both oxygen gas and hydrogen gas are used as reactants in a combustion reaction which produces heat. The produced heat may be used to heat the reactor. The produced heat may optionally be supplied to other downstream methods or apparatuses.

[0022] Further aspects and example embodiments are illustrated in the accompanying drawings and / or described in the following description.

[0023] It is emphasized that the invention relates to all combinations of the above features, even if these are recited in different claims.Brief Description of the Drawings

[0024] The accompanying drawings illustrate non-limiting example embodiments of the invention.

[0025] FIG. 1 is a schematic diagram illustrating a system for converting metal-ion containing solids to metal carbonates and / or silica and capturing and storing carbon dioxide using a two-chamber electrochemical cell, showing reactions that may occur in the electrochemical cell according to an example embodiment of the invention.

[0026] FIG. 2 is a flow chart illustrating the steps of a method for converting metal-ion containing solids to metal carbonates and / or silica and capturing and storing carbon dioxide using a two-chamber electrochemical cell according to an example embodiment of the invention.

[0027] FIG. 3A is a schematic diagram illustrating a system for converting metal-ion containing solids to metal carbonates and / or silica and capturing and storing carbon dioxide which integrates oxidation of a sulfur-containing species, showing reactions that may occur in the electrochemical cell according to an example embodiment of the invention.

[0028] FIG. 3B is a schematic diagram illustrating a system for converting metal-ion containing solids to metal carbonates and / or silica and capturing and storing carbon dioxide which integrates oxidation of a sulfur-containing species, showing reactions that may occur in the electrochemical cell according to another example embodiment of the invention.

[0029] FIG. 4 is a flow chart illustrating the steps of a method for converting metal-ion containing solids to metal carbonates and / or silica and capturing and storing carbondioxide which integrates oxidation of a sulfur-containing species according to an example embodiment of the invention.

[0026] FIG. 5 a schematic diagram illustrating a system for converting metal-ion containing solids to metal carbonates and / or silica and capturing and storing carbon dioxide using a three-chamber electrochemical cell, showing reactions that may occur in the electrochemical cell according to an example embodiment of the invention.

[0027] FIG. 6 is a flow chart illustrating the steps of a method for converting metal-ion containing solids to metal carbonates and / or silica and capturing and storing carbon dioxide using a three-chamber electrochemical cell according to an example embodiment of the invention.

[0030] FIG. 7A is a schematic diagram illustrating a continuous system for converting metal-ion containing solids to metal carbonates and / or silica and capturing and storing carbon dioxide using a two-chamber electrochemical cell, showing reactions that may occur in the electrochemical cell according to an example embodiment of the invention.

[0031] FIG. 7B is a schematic diagram illustrating a continuous system for converting metal-ion containing solids to metal carbonates and / or silica and capturing and storing carbon dioxide using a three-chamber electrochemical cell, showing reactions that may occur in the electrochemical cell according to an example embodiment of the invention.

[0032] FIG. 7C is a flow chart illustrating the steps of a continuous method for converting metal-ion containing solids to metal carbonates and / or silica and capturing and storing carbon dioxide according to an example embodiment of the invention.

[0033] FIG. 8A is a schematic diagram of a water electrolyzer described in the examples. The zero-gap configuration comprises an lrO2 composite anode, Nation™ CEM and Ni foam cathode separated pressed between titanium serpentine flowplates. In the anode chamber, OER converts H2O into H+and O2. The H+reacts with silicates to release Ca2+, which crosses the CEM into the cathode chamber. In the cathode chamber, HER converts H2O into gaseous H2 and OH-. The OH- reacts with CO2 to form carbonates, which in turn react with Ca2+to form CaCOs to capture and store carbon dioxide.

[0034] FIG. 8B is a plot of anolyte pH as a function of time (min) showing the anolytepH throughout 60 min of electrolysis both with 20 g L-1of CaSiOs and without any CaSiOs. The higher pH in the presence of CaSiOs indicates consumption of acid generated by the water electrolyzer.

[0035] FIG. 9A is a powder XRD diffractogram of the precipitate collected following 1 h of electrolysis at 100 mA cm-2. Anolyte contained 20 g L-1of milled CaSiOs and the catholyte was bubbled with CO2 to maintain steady state pH of 11 .

[0036] FIG. 9B is a plot of full cell voltage (V) as a function of time (min). The plot shows the voltage of the water electrolyzer during electrolysis at 100 mA cm-2.

[0037] FIG. 10 is a schematic diagram of a sulfite electrolyzer described in the examples. The zero-gap configuration consists of a Pt composite anode, Nation™ CEM and Ni foam cathode separated pressed between titanium serpentine flowplates. In the anode chamber, SO3OR converts SO32-and H2O into H+and SO42-. In the cathode chamber, HER converts H2O into gaseous H2 and OH-.

[0038] FIG. 11 A is a plot of full cell voltage (V) as a function of time (min). The plot shows voltage traces from electrolysis experiments performed for 60 minutes at an applied current density of 100 mA cm-2.

[0039] FIG. 11 B is a plot of full cell voltage (V) as a function of current density (mA cm-2) showing polarization curves for the water electrolyzer and the sulfite electrolyzer. The voltage was recorded following 5 minutes of electrolysis at each current density.

[0040] FIG. 12A is a powder XRD diffractogram of the precipitate collected from the catholyte following 60 minutes of electrolysis at 100 mA cm-2in the integrated sulfite electrolyzer. During this experiment, the catholyte (containing 1.0 M NaCI and 0.5 M MgSO4) was bubbled with CO2 to maintain a pH between 9.5-10.

[0041] FIG. 12B is a plot showing the rate of carbon storage in the integrated sulfite electrolyzer at current densities between 100-400 mA cm-2.

[0042] FIG. 13 is a schematic diagram of a weathering electrolyzer described in the examples.

[0043] FIG. 14A is a plot of catholyte pH as a function of time (min). The plot shows catholyte pH during 1 hour of electrolysis at a current density of 100 mA cm-2, with and without CaSiOs present. The chemical compartment was fed with a circulating chemolyte containing a 1.0 M CaC solution with and without the addition of 10 g L-1CaSiOs. The higher pH with CaSiOs present is a result of CaSiOs reacting with H+from the membrane to form Ca2+(aq), SiO2(S) and H2O.

[0044] FIG. 14B is a plot showing Ca2+concentration [Ca2+(aq)] in the chemical and cathode chambers during 1 hour of electrolysis at 100 mA cm-2.

[0045] FIG. 15A is a plot illustrating catholyte pH as a function of electrolysis at 100 mA cm-2with and without CaSiOs added to the chemical chamber, and with and without CO2 added to the cathode chamber. Simulated flue gas (10% CO2, 90 % N2) was delivered at flow rate of 200 seem, air at 2000 seem.

[0046] FIG. 15B are powder X-ray diffractograms of solids collected from the cathode chamber after the same electrolysis experiments with simulated flue gas and ambient air.

[0047] FIG. 16A is a plot comparing the CO2 mineralization rate (tco2t'1siiicateyr1) between the weathering electrolyzer described in this application and the natural rock weathering processes. Proof of concept experiments have demonstrated that electrolysis using the described systems and methods can accelerate natural rock weathering by at least three orders of magnitude.

[0048] FIG. 16B is a graph illustrating sequestration efficiency where CO2 is sourced from both ambient air and simulated flue gas.

[0049] FIG. 16C is a graph illustrating carbonation efficiency of weathering electrolyzer where CO2 is sourced from both ambient air and simulated flue gas.

[0050] FIG. 17 are plots illustrating sequestration efficiencies (top) and carbonation efficiencies (bottom) of 1 hour electrolysis for the weathering electrolyzer with air purging into catholyte with varied amino acid (salt) at flow rate of 2000 seem. Glycine (Gly) and potassium glycinate (Gly-K) are used as amino acid and amino acid salt. Total amino acid (salt) concentration varied from 0.1 to 1 M.

[0051] FIG. 18 are plots illustrating cell voltage profile of the weathering electrolyzer over 1 hour electrolysis with air purging at flow rate of 2000 seem into catholyte with amino acid (salt) at concentration of 1 M (top) and 0.1 M (bottom). Glycine (Gly) and potassium glycinate (Gly-K) are used as amino acid and amino acid salt.

[0052] FIG. 19 are XRD profiles of calcium carbonate obtained from the cathode chamber of the weathering electrolyzer over 1 hour electrolysis with air purging at flow rate of 2000 seem into catholyte with amino acid (salt) at concentration of 0.1 M.Glycine (Gly) and potassium glycinate (Gly-K) are used as amino acid and amino acid salt.Detailed Description

[0053] Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive sense.Definitions

[0054] A “metal-ion containing solid” refers to a hardened composition which comprises a metal ion. A hardened composition generally does not flow perceptibly and that substantially retains its shape under moderate stress, pressure or gravity. Minerals (e.g., silicate minerals), rocks (e.g., dunite (ultramafic, high forsterite olivine), peridotite (ultramafic, olivine + pyroxene), serpentinite (metamorphic, serpentine minerals), basalt (mafic, Ca-rich plagioclase + pyroxene), gabbro (intrusive equivalent of basalt), dolostone (carbonate, dolomite-dominant), limestone (carbonate, calcite / aragonite-dominant), marble (metamorphic, recrystallized calcite / aragonite), carbonatite (igneous, carbonate minerals)), and oxides (e.g., periclase (MgO), lime (CaO), brucite (Mg(OH)2), portlandite (Ca(OH)2)) are examples of such hardened composition. The metal-ion containing solid may be a compound which comprises any suitable metal ions. In some embodiments of the invention, the metal-ion containing solid comprises a divalent cation such as magnesium (Mg2+), iron (Fe2+), zinc (Zn2+), and calcium (Ca2+), etc.

[0055] “Silicate mineral” is a solid material which contains the structural unit, SiO4. Non-limiting examples of silicate minerals include wollastonite (CaSiOs), olivine - forsterite (Mg2SiO4), olivine (Mg,Fe)2SiO4; pyroxene - enstatite (MgSiO3), diopside (CaMgSi2O6), augite ((Ca,Mg,Fe)2Si2O6); amphibole - tremolite (Ca2Mg5Si8O22(OH)2), actinolite (Ca2(Mg,Fe)5Si8O22(OH)2); serpentine - lizardite (Mg3Si2O5(OH)4), chrysotile (Mg3Si2O5(OH)4), antigorite (Mg3Si2O5(OH)4); talc(Mg3Si4Oio(OH)2); chlorite ((Mg,Fe)5AI2Si3Oio(OH)8); garnet - pyrope (Mg3AI2Si3Oi2), grossular (Ca3AI2Si3Oi2), andradite (Ca3Fe2Si3Oi2); epidote - clinozoisite (Ca2AI3Si3Oi2(OH)), epidote (Ca2(AI,Fe)3Si3Oi2(OH)); vesuvianite (Caio(Mg,Fe)2Al4Si9034(OH)4); staurolite ((Fe,Mg,Zn)2AI9Si4O23(OH)); biotite (K(Mg,Fe)3AISi3O10(OH)2); phlogopite (KMg3AISi3O10(OH)2).

[0056] “Bipolar membrane” or “BPM” is a membrane comprising plural layers including an anion exchange layer on one side and a cation exchange layer on another side. A bipolar membrane may comprise one or more layers between the anion exchange layer and the cation exchange layer. For example, an intermediate layer may comprise a catalyst which facilitates dissociation of water into protons and hydroxide ions. The anion exchange layer may conduct hydroxide ions. The cation exchange layer may conduct protons. An example bipolar membrane is Fumasep FBM™ available from FUMATECH BWT GmbH.

[0057] “Microporous polymer membrane” is a membrane that is made of a polymeric material which has micropores distributed within it. In some embodiments, the micropores are joined to allow gas and / or liquid to pass therethrough from one side to another. In some embodiments, the average micropores in the microporous polymer membrane have a diameter of 2 nm or more than 2 nm. An example microporous polymer membrane is Celgard® 3501 available from Celgard.

[0058] “Current density” is total current divided by the geometric surface area of an electrode. For example, an electrode having an area of 100 cm2carrying an electrical current of 20 Amperes would have a current density of 200 mA cm-2.

[0059] “Flow field” is a structure such as a plate (or a flow plate) which provides at path (e.g., channels, apertures, grooves etc. formed in the structure) through which a substance such as a liquid and / or gas (e.g., reactants, products and / or electrolyte, etc.) is supplied to and / or out of an electrode. Examples of flow field structures include straight parallel, interdigitated, single-channel serpentine, or multiple-channel serpentine, which may be 3D printed into a flow plate or machined out of a flow plate material.

[0060] “Flow cell” refers to an electrochemical cell in which a catholyte and / or anolyte are flowed through the cell while the cell is in operation. A non-limiting example construction of a flow cell provides flow plates separated by a membrane electrodeassembly (MEA). An anode flow plate is located at the anode side of the MEA and a cathode flow plate is located at the cathode side of the MEA. The anode and cathode flow plates comprise flow channels that respectively receive an anode feed and a cathode feed. A power supply is connected across the anode and cathode of the MEA in the flow cell to drive oxidation reactions at the anode and reduction reactions at the cathode.

[0061] “Ion exchange membrane” is a membrane that has a significantly higher permeability for certain dissolved ions than for other ions. Ideally an ion exchange membrane would pass ions of a selected species or type (e.g. cations or anions) while blocking other ions.

[0058] “Cation exchange membrane” or “CEM” is a membrane that is selectively permeable to cations. An example cation exchange membrane is Nation™. A cation exchange membrane is an example of an ion exchange membrane which is adapted to selectively pass cations while blocking other ions. Examples of materials which may be suitable to form cation exchange membranes include sulfonated polystyrene, perfluorosulfonic acid (e.g., Nation™), aromatic hydrocarbon (e.g., sulfonated poly(arylene ether sulfone), polybenzimidazole, and other aromatic polymers), hybrid organic and inorganic materials (e.g., sulfonated polymers with inorganic fillers like silica, zirconia, or titania) composite materials (e.g., thin cation exchange layer supported by a non-exchangeable, mechanically robust layer), modified natural polymer (e.g., cellulose or chitosan), or polystyrene-divinylbenzene (PS-DVB). A cation exchange membrane may be treated, functionalized or otherwise modified to alter the membrane’s selectivity or affinity to selected ion(s), such as to enhance affinity to desired ion(s). For example, one method is to saturate the membrane in a concentrated solution of the desired cation, thus replacing existing counter-ions and enhancing the membrane's affinity for the desired ions. Other example methods include functionalizing the membrane with sulfonic and / or carboxylic groups to increase ion affinity, using layer-by-layer (LbL) assembly with polyelectrolytes to create selective transport pathways, and incorporating ion-selective nanochannels or metal-organic frameworks (MOFs) to tailor ion transport. A further example method includes crosslinking with chelating agents such as EDTA can selectively bind divalent ions, while adjusting pore size and surface charge density can furtherenhance selectivity. An even further example method is surface grafting of the membrane with zwitterionic polymers which can improve divalent ion selectivity through hydration layers. The cation exchange membrane may be treated, functionalized or otherwise modified to alter the membrane to preferentially block passage of selected ion(s). This may be done for example by adding a coating layer (e.g., a coating layer comprising one or more of polyaniline (PANI), polydopamine, and / or sulfonated polyether ether ketone, etc.) and / or grafting on the surface of the membrane a layer of polymer such as polyethylene glycol (PEG).

[0062] “Oxygen evolution reaction” or “OER” is the process of generating molecular oxygen by an electrochemical reaction. An example of an oxygen evolution reaction is the oxidation of hydroxide, in accordance with Equation 6.4OH'(aq) — 2H2O(|) + O2(g)+ 4e'(6)

[0063] “Hydrogen evolution reaction” or “HER” is the process of producing hydrogen by an electrochemical process. An example of a hydrogen evolution reaction is the reduction of water, in accordance with Equation 7.2H2O(|) + 2e~ —> H2(g) + 2OH'(aq)(7)

[0064] “Oxidation state” refers to the electrically neutral state or to the state produced by the gain or loss of electrons to an element, compound, or chemical substituent / subunit. The phrase “higher oxidation state” refers to a higher of at least two available oxidation states for a particular metal or nonmetal and the phrase “lower oxidation state” refers to a lower of at least two available oxidation states for the particular metal or nonmetal.

[0065] “Carbon dioxide feedstock” means a feedstock comprising carbon dioxide, the molecule CO2, which is in gas, liquid, supercritical liquid, and / or solid form or phase, optionally mixed with other gases, liquids and / or solids. Examples of a carbon dioxide feedstock include a capture solution (i.e. , an aqueous solution comprising bicarbonate and carbonate), air, flue gas, pure carbon dioxide gas, and combinations thereof.

[0066] “Source of a carbon dioxide feedstock” means one or more apparatusesconfigured to collect and / or store the carbon dioxide feedstock. The source of the carbon dioxide feedstock may optionally comprise one or more apparatuses configured to filter, concentrate and / or otherwise treat the carbon dioxide feedstock after being collected and prior to storage to prepare a carbon dioxide feedstock that is suitable for use in subsequent reactions. As one example, the source of a carbon dioxide feedstock comprises an air contactor. The air contactor may be configured to bring a gas comprising carbon dioxide, into contact with an aqueous solution (e.g., any suitable CO2 aqueous capture solution such as an alkaline solution) to absorb and chemically react gaseous carbon dioxide to form bicarbonate and / or carbonate in an aqueous solution. As another example, the source of the carbon dioxide feedstock may comprise air collectors and / or flue gas collectors.Systems and methods for converting metal-ion containing solids for carbon dioxide capture and storage using a two-chamber cell

[0067] Aspects of the invention relate to systems and methods of converting metalion containing solids for carbon dioxide capture and storage using a two-chamber cell. FIG. 1 is a schematic diagram which illustrates an example system 10 for such conversion of metal-ion containing solids. The illustrated embodiment shows the production of metal carbonate and silica (or silicon dioxide, SiC>2). In such embodiments, the metal-ion containing solid comprises a silicate containing compound. However, the system 10 may be operable to produce other one or more compounds. The produced one or more compounds may depend on the composition of the metal-ion containing solids. The system 10 comprises an electrochemical cell 14 and a source of carbon dioxide feedstock 11 in fluid communication with the cell 14 such that the carbon dioxide feedstock 11 is supplied into the cell 14 for reaction to yield metal carbonates 90.

[0068] One application of this system and method is in carbon capture and storage. The system 10 provides an integrated system for carbon dioxide capture and storage in a water electrolyzer.

[0069] Proof of concept experiments have demonstrated that stable operation can be achieved at a cell voltage of 3 V at an industrially relevant current density of 100 mA cm-2.Example system of producing metal carbonates using a two-chamber cell

[0070] Referring to FIG. 1 , the cell 14 comprises an anode chamber 18 and a cathode chamber 20. A cathode 22 is exposed to the cathode chamber 20. An anode 19 is exposed to the anode chamber 18. A separator 24 separates the anode chamber 18 and the cathode chamber 20.

[0071] In some embodiments, the cell 14 comprises a zero-gap, water electrolyzer. In such embodiments, the anode 18 and cathode 22 are pressed against the separator 24. A distance between the anode 18 and the cathode 22 is the thickness of the separator 24.

[0072] In some embodiments, the separator 24 is adapted to selectively permeate specific metal ions such as the metal ion in the metal-ion containing solids that is fed into the system 10 for processing. Such specific metal ions may for example comprise one or more divalent cations, such as but are not limited to calcium ions (Ca2+), and magnesium ions (Mg2+).

[0073] In some example embodiments, the separator 24 comprises an ion exchange membrane such as a cation exchange membrane. The separator 24 may however comprise other types of membrane layers which are adapted to permit one or more cations to permeate therethrough. A non-limiting example of such other types of membrane layer comprises a microporous polymer membrane.

[0074] A power source 32 is connected to apply an electrical potential difference between the cathode 22 and the anode 19. A negative electrical charge is applied to the cathode 22. A positive electrical charge is applied to the anode 19.

[0075] The power source may be configured to maintain a desired electric current between the cathode 22 and the anode 19 and / or to maintain a potential difference between the cathode 22 and the anode 19 at a desired level or in a desired range.

[0076] An oxidation reaction 34 takes place at the anode 19. A reduction reaction 36 takes place at the cathode 22.

[0077] An oxidation reactant 44 participates in the oxidation reaction 34 to form an oxidation product 46. In some embodiments, the oxidation reaction 34 comprises an oxygen evolution reduction (OER). In such embodiments, the oxidation reactant 44 comprises a hydrogen-containing reactant 43. In some embodiments, a reservoircontaining the hydrogen-containing reactant 43 may be fluidly connected to supply the hydrogen-containing reactant 43 to the anode 19. In some embodiments, the oxidation product 46 comprises hydrogen ions 45.

[0078] A hydrogen-containing reactant 38 participates in the reduction reaction 36 to generate hydroxide ions 30. In some embodiments, the reduction reaction comprises a hydrogen evolution reaction (HER). In such embodiments, the hydrogen-containing reactant 38 comprises water. A reservoir comprising the hydrogen-containing reactant 38 may be fluidly connected to supply the hydrogen-containing reactant 38 to the cathode chamber 20.

[0079] The cathode 22 may comprise any materials suitable for use as an electrode. Such material may, for example comprise a catalyst suitable for driving a hydrogen evolution reaction (HER).

[0080] The anode 19 may comprise any materials suitable for use as an electrode. Such material may comprise a catalyst suitable for driving an oxygen evolution reaction (OER).

[0081] The cathode 22 and / or anode 19 may be a gas diffusion electrode.

[0082] The cathode 22 and / or anode 19 may be made of one or more metal, alloy or a supported metal / alloy catalyst. The metal may be any transition metal, or combination of one or more transition metals.

[0083] Suitable electrocatalyst that may be incorporated in the cathode 22 may, for example, comprise one or more of C, Pt, Fe, Co, Mo, and combinations thereof.

[0084] Suitable electrocatalyst that may be incorporated in the anode 19 may, for example, comprise one or more of Pt, Rh, Ir, Ru, Pd, Ni, and combinations thereof.

[0085] The cathode 22 and / or anode 19 may be porous. An example of a porous electrode is an electrode comprising an electrically conductive foam such as a metal foam. In some example embodiments, the cathode 22 and / or anode 19 comprises a layer of porous nickel (Ni) foam. The nickel foam layer may be free-standing or supported (e.g. by other components of an MEA).

[0086] Non-limiting examples of suitable materials to form the anode 19 include lrC>2 with carbon, Pt with carbon, Pt felt, Pt mesh, Au with carbon, RuC>2 with carbon, Iridum-ruthenium oxides, Ni foam, Ni on carbon or carbon paper and the like.

[0084] Non-limiting examples of suitable materials to form the cathode 22 include Nifoam, Ni with carbon, Pt with carbon, Pt felt, CoPc with carbon, RuC>2 with carbon, Fe- Ni with carbon, Cu with carbon, Cu-Ni with carbon, M0S2 with carbon or carbon paper and the like.

[0087] In some embodiments, a suitable anolyte 54 is supplied to the anode chamber 18.

[0088] In some embodiments, the anions of the anolyte 54 are monovalent. The anions of the anolyte 54 may for example comprise one or more of fluoride (F-), chloride (Cl-), bromide (Br), and iodide (I-), nitrate (NO3_), and nitrite (NC>2'), acetate (CH3COO_), trifluoroacetate (CF3COO_), perchlorate (CIO4 ), chlorate (CIOs'), perchlorate (CIO4 ), sulfate (SO42'), bisulfate (HSO4‘), bromate (BrOs'), perbromate (BrO4‘), formate (HCOO'), propanoate (C2HsCOO'), lactate (CsHsOs'), trihalide acetate (CX3COO_, where X=F, Cl, Br, I), triflate (CFsSOs'), and bistriflimide ([(CF3SO2)2N]'), etc.

[0089] In some embodiments, the cations of the anolyte 54 are monovalent and / or divalent. The cations of the anolyte 54 may for example comprise one or more of an alkaline earth metal ions e.g., calcium (Ca2+), magnesium (Mg2+), or a transition metal ion (e.g., Fe2+), etc., and / or alkali metal ions, e.g., lithium (Li+), sodium (Na+), potassium (K+), rubidium (Rb+), cesium (Cs+), ammonium (NH4+), etc.

[0090] In some embodiments, a reservoir containing the anolyte 54 and / or a metal-ion containing solids 74 is connected to supply the anolyte 54 and / or the metal-ion containing solids 74 to the anode chamber 18. The metal-ion containing solids 74 may be provided as an aqueous slurry of microparticles. The metal-ion containing solids 74 are caused to react with the hydrogen ions 45 formed in the oxidation reaction 34 to yield metal ions 76. In some embodiments, the metal-ion containing solids 74 comprise a silicate containing mineral. In such embodiments, the reacting of the metal-ion containing solid 74 with the hydrogen ions 45 formed in the oxidation reaction 34 additionally produces silica 75.

[0091] In some embodiments, the separator 24 is adapted to selectively permeate the metal ions 76 through the separator 24 from the anode chamber 18 to the cathode chamber 20.

[0092] In some embodiments, a reservoir containing a catholyte 56 is supplied to the cathode chamber 20.

[0093] In some embodiments, the anions of the catholyte 56 may comprise a divalent anion (e.g., sulfate ion (SC>42'), and / or a monovalent anion such as one or more of fluoride (F'), chloride (Cl-), bromide (Br), and iodide (I-), nitrite (NCh-), acetate (CHsCOO-), trifluoroacetate (CFsCOO'), perchlorate (CIO4 ), chlorate (CIOs'), perchlorate (CIO4‘), sulfate (SO42'), bisulfate (HSO4‘), bromate (BrOs'), perbromate (BrO4‘), formate (HCOO'), propanoate (CsHsCOO'), lactate (CsHsOs'), trihalide acetate (CX3COO-, where X=F, Cl, Br, I), triflate (CF3SO3-), and bistriflimide ([(CF3SO2)2N]'), etc.

[0094] The cations of the catholyte 56 may for example be a divalent cation such as an alkaline earth metal ions e.g., calcium (Ca2+), magnesium (Mg2+), or a transition metal ion (e.g., Fe2+), etc., or a monovalent cation such as an alkali metal, e.g., lithium (Li+), sodium (Na+), potassium (K+), rubidium (Rb+), and cesium (Cs+), ammonium (NH4+) etc.

[0095] In some embodiments, a first inlet 86 is provided at the cathode chamber 20. The first inlet 86 is fluidly connected to an outlet 84 of the source of the carbon dioxide feedstock 11 , adapted to discharge a flow of the carbon dioxide feedstock 85 into the cathode chamber 20. In some embodiments, an air distributor is fluidly connected to the first inlet 86 at the cathode chamber 20. The air distributor may be configured to distribute a gaseous carbon dioxide feedstock 85 in the catholyte 56.

[0096] The carbon dioxide feedstock 85 reacts with the hydroxide ions 30 formed in the reduction reaction 36 and the metal ions 76 produced in the anode chamber 18 to yield metal carbonate 90.Example method of converting metal-ion containing solids for carbon dioxide capture and storage using a two-chamber cell

[0097] FIG. 2 is a flow chart illustrating a method 200 of converting metal-ion containing solids for carbon dioxide capture and storage according to one example embodiment of the invention.

[0098] In block 202, an electrical current and / or potential is applied between an anode and a cathode.

[0099] In block 203, a flow of a first hydrogen-containing reactant is supplied to the cathode chamber. The first hydrogen-containing reactant may be contained in thecatholyte or may be separately supplied to the cathode.

[0100] In block 206, the first hydrogen-containing reactant undergoes a reduction reaction at the cathode to produce hydroxide ions. The reduction reaction may comprise a hydrogen evolution reaction (HER).

[0101] In block 208, a flow of a second hydrogen-containing reactant is supplied to the anode. The second hydrogen-containing reactant may be contained in the anolyte or may be separately supplied from the anolyte.

[0102] In block 210, the second hydrogen-containing reactant undergoes an oxidation reaction at the anode to produce hydrogen ions. The oxidation reaction may comprise an oxygen evolution reaction (OER).

[0103] A flow of metal-ion containing solid is supplied to the anode chamber (block 212). In some embodiments, the metal-ion containing solid is pre-treated before being supplied to the anode chamber. In some example embodiments, the pre-treating comprises grinding the metal-ion containing solid, for example to an average diameter of less than about 1 mm. The ground metal-ion containing solid may be suspended into a liquid to form an aqueous slurry comprising microparticles. The metal-ion containing solid may be contained in the anolyte or be separately supplied to the anode chamber.

[0104] In block 214, the metal-ion containing solid reacts with the hydrogen ions produced in the oxidation reaction to generate metal ions. In embodiments in which the metal-ion containing solid comprises silicate minerals, the reacting of the metalion containing solid with the hydrogen ions produces a silicon-containing by-product. In some embodiments, the silicon-containing by-product comprises silica (SiC>2).

[0105] In block 216, the metal ions permeate through a separator from the anode chamber to the cathode chamber.

[0106] In block 218, a flow of carbon dioxide feedstock is supplied into the cathode chamber. The carbon dioxide feedstock reacts with the metal ions permeated from the anode chamber and the hydroxide ions formed in the reduction reaction to yield metal carbonates (block 220).

[0107] The method 200 may be tuned to optimize one or more of current efficiency, applied electrical potential to achieve a desired current efficiency, product selectivity, efficiency and reaction rate of each of the reactions by adjusting one or more of:• conditions of the flow cell such as temperature, pH, pressure, etc.; and / or• characteristics of the separator such as the thickness, porosity, composition, etc.; and / or• characteristics of the anode and / or cathode electrodes such as the material and method of fabrication; and / or• nature of the cathode and / or anode catalyst;• additional catalysts present; and / or• the type of anolyte and catholyte; and / or• flow rate and / or composition and / or concentration of the oxidation reactant, reduction reactant, metal-ion containing solids, carbon dioxide feedstock, catholyte, and / or anolyte; and / or• rate at which metal carbonates are removed from the cell; etc.

[0108] In some embodiments, the electrical potential difference applied between cathode 22 and anode 19 to maintain the current density at a level of at least 100 mA cm-2is about 3 V. In some embodiments of the method, the current density is maintained at a level between 50 mA cm-2and 200 mA cm-2. In some embodiments of the method, the current density is maintained at a level between 200 mA cm-2and 500 mA cm-2. In some embodiments of the method, the current density is maintained at a level between 500 mA cm-2and 1000 mA cm-2.

[0109] In some embodiments, the electrolysis is operated at a temperature in the range of from 25 °C to about 60 °C. In some embodiments, the electrolysis is operated at a temperature less than about 60 °C.

[0110] In some embodiments, the anolyte 54 and / or catholyte 56 are heated to a selected temperature before being supplied to the anode chamber 18 and cathode chamber 20 respectively. In some embodiments, the anolyte 54 and / or catholyte 56 are heated to a temperature in the range of from about 20 °C to about 60 °C.

[0111] In some example embodiments, the separator 24 comprises an ion exchange membrane. The thickness of the ion exchange membrane may be in the range of from about 20 to about 200 pm. In some embodiments, the separator 24 is a Nation™ 117 membrane.

[0112] In some embodiments, a flow rate at which the anolyte 54 and / or the catholyte 56 are supplied to the respective anode chamber 18 and cathode chamber 20 mayfor example be in the range of from about 30 to about 800 mL min-1including any value or subrange therebetween for an electrode having a geometric surface area of 4 cm2. The flow rate may be scaled according to the area of the electrode. In some embodiments, a flow rate at which the anolyte 54 and / or the catholyte 56 are supplied to the respective anode chamber 18 and cathode chamber 20 is in the range of from about 50 to about 350 mL min-1including any value or subrange therebetween for an electrode having a geometric surface area of 4 cm2.

[0113] In some embodiments, the concentration of the anolyte 54 and / or the catholyte 56, supplied to the respective anode chamber 18 and cathode chamber 20 is up to about 1 .0 M, including any value or subrange greater than 0 and between 0 and 1 .0 M.

[0114] In some embodiments, the pH within the cathode chamber 20 is maintained in the range of from about 9 to about 13 including any value and subrange therebetween, during electrolysis, and in some embodiments, between about 9 to about 11.

[0115] In some embodiments, the pH within the anode chamber 18 is maintained in the range of from about 1 to about 10 including any value and subrange therebetween, during electrolysis, and in some embodiments, less than about 4.

[0116] In some embodiments, a concentration of the metal-ion containing solid being supplied to the anode chamber is in the range of from about 0.01 to about 60 g / L, including any value or subrange therebetween.

[0117] In some example embodiments in which carbon dioxide feedstock comprises air, the concentration of the carbon dioxide supplied to the cathode chamber is up to about 400 ppm, including any value or subrange greater than 0 and between 0 to 400 ppm.

[0118] In some example embodiments in which the carbon dioxide feedstock comprises flue gas, the concentration of the carbon dioxide supplied to the cathode chamber is between about 3 to 40 vol%, and in some embodiments, between 5-20 vol%, including any value or subrange therebetween.

[0119] In some example embodiments in which carbon dioxide feedstock comprises air, a flow rate at which the carbon dioxide feedstock is supplied to the cathode chamber 20 may for example be up to about 2000 seem including any value orsubrange therebetween, for an electrode having a geometric surface area of 4 cm2. The flow rate may be scaled according to the area of the electrode.

[0120] In some example embodiments in which carbon dioxide feedstock comprises flue gas, a flow rate at which the carbon dioxide feedstock is supplied to the cathode chamber 20 may for example be in the range of from about 50 to 200 seem, including any value or subrange therebetween, for an electrode having a geometric surface area of 4 cm2. The flow rate may be scaled according to the area of the electrode.

[0121] In summary, one example aspect of the invention provides systems and methods of converting metal-ion containing solids to metal carbonates. This conversion may involve the conversion of a silicate mineral (e.g., CaSiOs) to calcium carbonate (CaCOs) and silica (SiC>2). It will however be understood that the systems and methods described herein may be used to convert any suitable metal-ion containing solids to metal carbonates.

[0122] One aspect of the invention provides a water electrolyzer configured for carbon dioxide capture and storage. Such water electrolyzer may also be referred to herein as a “two-chamber water electrolyzer”.

[0123] The example water electrolyzer comprises two chambers. The water electrolyzer comprises an anode chamber and a cathode chamber. A cation exchange membrane separates the anode chamber from the cathode chamber. The water electrolyzer may comprise a zero-gap configuration having the anode, cation exchange membrane and cathode being pressed between two spaced flow plates.

[0124] An oxygen evolution reaction (OER) may occur at the anode. The OER may convert the oxidation reactant, e.g., water, into hydrogen ions and oxygen gas.

[0125] A slurry of silicate containing mineral (e.g., CaSiOs) contained in an anolyte (e.g., KNO3) may be supplied to the anode chamber. The hydrogen ions generated at the anode react with the silicate (e.g., CaSiOs) to release metal ions (e.g., Ca2+), and additionally produces silica (SiC>2). The metal ions (e.g., Ca2+) crosses the cation exchange membrane into the cathode chamber.

[0126] A hydrogen evolution reaction (HER) may occur at the cathode. The HER may convert the reduction reactant, e.g., water, into hydroxide ions and hydrogen gas.

[0127] A feedstock comprising carbon dioxide is supplied into the cathode chamber. The carbon dioxide reacts with the hydroxide ions and the metal ions (e.g., Ca2+) toyield metal carbonate (e.g., CaCOs).Example systems and methods for converting metal-ion containing solids for carbon dioxide capture and storage which integrate the oxidation of sulfur-containing species

[0128] Aspects of the invention relate to particularly efficient systems and methods of converting metal-ion containing solids for carbon dioxide capture and storage. Such particularly efficient methods integrate the oxidation of a sulfur-containing species at the anode to generate hydrogen ions for the dissociation of metal-ion containing solids in generating metal ions that may be brought in contact with a carbon dioxide feedstock and hydroxide ions produced at the cathode to yield metal carbonates. In embodiments in which the metal-ion containing solids comprise a silicate containing mineral, the dissociation of the metal-ion containing solids with hydrogen ions may additionally produce silica.

[0129] Proof of concept experiments have demonstrated that such systems can operate at an electrical potential applied between the cathode and the anode of only about 2.2 V while maintaining a current density of 100 mA cm-2.Example systems of converting metal-ion containing solids for carbon dioxide capture and storage which integrate the oxidation of sulfur-containing species

[0130] FIGS. 3A and 3B illustrate example systems 1000, 1100 that may be used for converting metal-ion containing solids to metal carbonates which integrate the oxidation of sulfur-containing species. Referring to FIG. 3A and 3B, the cell 14 comprises an anode chamber 18 and a cathode chamber 20. A cathode 22 is exposed to the cathode chamber 20. An anode 19 is exposed to the anode chamber 18. A separator 24 separates the anode chamber 18 and the cathode chamber 20.

[0131] In some embodiments, the cell 14 comprises a zero-gap, two chamber electrolyzer. In such embodiments, the anode 18 and cathode 22 are pressed against the separator 24. A distance between the anode 18 and the cathode 22 is the thickness of the separator 24.

[0132] In some embodiments, the separator 24 is adapted to block passage of the metal ion in the metal-ion containing solids that is fed to the system 1000, 1100 for processing. A coating layer may be provided on the separator 24. In some exampleembodiments, the coating layer comprises a polymer such as polyaniline (PANI).

[0133] In some embodiments, the separator 24 is adapted to selectively permeate specific metal ions such as the metal ion in the metal-ion containing solids that is fed into the system 1000, 1100 for processing.

[0134] Such specific metal ions may for example comprise one or more divalent cations, such as but are not limited to calcium ions (Ca2+), and magnesium ions (Mg2+).

[0135] In some example embodiments, the separator 24 comprises an ion exchange membrane such as a cation exchange membrane. The separator 24 may however comprise other types of membrane layers which are adapted to pass or block one or more cations therethrough. A non-limiting example of such other types of membrane layer comprises a microporous polymer membrane.

[0136] A power source 32 is connected to apply an electrical potential difference between the cathode 22 and the anode 19. A negative electrical charge is applied to the cathode 22. A positive electrical charge is applied to the anode 19.

[0137] The power source may be configured to maintain a desired electric current between the cathode 22 and the anode 19 and / or to maintain a potential difference between the cathode 22 and the anode 19 at a desired level or in a desired range.

[0138] An oxidation reaction 34 takes place at the anode 19. A reduction reaction 36 takes place at the cathode 22.

[0139] A hydrogen-containing reactant 38 participates in the reduction reaction 36 to generate hydroxide ions 30. In some embodiments, the reduction reaction comprises a hydrogen evolution reaction (HER). In such embodiments, the hydrogen-containing reactant 38 comprises water. A reservoir comprising the hydrogen-containing reactant 38 may be fluidly connected to supply the hydrogen-containing reactant 38 to the cathode chamber 20.

[0140] An oxidation reactant 44 participates in the oxidation reaction 34 to form an oxidation product 46. The oxidation reactant 44 comprises a sulfur-containing species with a sulfur atom in a lower oxidation state 47. The sulfur-containing species with the sulfur atom in the lower oxidation state 47 participates in the oxidation reaction 34 to form a sulfur-containing species with a sulfur atom in a higher oxidation state 51. In some embodiments, the oxidation state of the sulfur-containing species with the sulfuratom in the lower oxidation state 47 is in the range of from -2 to +5, or any value or subrange therebetween. In some embodiments, the oxidation state of the sulfur- containing species with the sulfur atom in the higher oxidation state 51 is in the range of from -1 to +6, or any value or subrange therebetween.

[0141] In some embodiments, the sulfur-containing species with the sulfur atom in the lower oxidation state 47 is supplied from a feedstock which comprises sulfur- containing species that are sourced from a waste stream such as byproducts generated from industrial processes including coal combustion, oil refining, metal ore processing, etc. Such feedstock may also be referred to herein as “sulfurous waste”.

[0142] Non-limiting examples of the sulfur-containing species with a sulfur atom in the lower oxidation state 47 include one or more of hydrogen sulfide (H2S), bisulfide (HS_), sulfide (S2-), disulfide (S22'), polysulfide (Sx2‘; wherein x=2-8), elemental sulfur (Sx, wherein x =6-20), thiosulfate (S2Os2'), dithionite (S2C>42'), sulfur dioxide (SO2), sulfite (SO32’), bisulfite (HSOs'), metabisulfite (S2Os2'), dithionate (S2Oe2'), and polythionates [O3S(SX-2)SO3]2'; wherein x=3-8, 10, 12, 14.

[0143] Non-limiting examples of the sulfur-containing species with a sulfur atom in the higher oxidation state 51 include one or more of disulfide (S22'), polysulfide (Sx2-; wherein x=2-8), elemental sulfur (Sx, wherein x =6-20), thiosulfate (S2O32'), dithionite (S2O42), sulfur dioxide (SO2), sulfite (SOs2-), bisulfite (HSOs'), metabisulfite (S2Os2'), dithionate (S2Oe2'), polythionates [O3S(SX-2)SC>3]2'; wherein x=3-8, 10, 12, 14, sulfur trioxide (SO3), sulfate (SC>42'), bisulfate (HSCU , pyrosulfate (S2O?2'), and peroxysulfate (S2Os2')-

[0144] In some embodiments, the oxidation reaction 34 is performed in the presence of a hydrogen-containing reactant 43. The hydrogen-containing reactant 43 may serve as a source of protons in the oxidation reaction 34. In some example embodiments, the hydrogen-containing reactant 43 comprises water. In some embodiments, the oxidation product 46 additionally comprises hydrogen ions 45.

[0145] In some embodiments, a reservoir containing the sulfur-containing species with a sulfur atom in the lower oxidation state 47 and the hydrogen-containing reactant 43 is fluidly connected to supply the sulfur-containing species with a sulfur atom in the lower oxidation state 47 and the hydrogen-containing reactant 43 to the anode 19. The sulfur-containing species with a sulfur atom in the lower oxidation state47 and the hydrogen-containing reactant 43 may alternatively be separately supplied to the anode 19. In some embodiments, the anolyte 54 comprises the hydrogencontaining reactant 43.

[0146] The cathode 22 may comprise any materials suitable for use as an electrode. Such material may, for example comprise a catalyst suitable for driving a hydrogen evolution reaction (HER).

[0147] The anode 19 may comprise any materials suitable for use as an electrode. Such material may comprise a catalyst suitable for driving oxidation of a sulfur- containing species, such as but is not limited to sulfite.

[0148] The cathode 22 and / or anode 19 may be a gas diffusion electrode.

[0149] The cathode 22 and / or anode 19 may be made of one or more metal, alloy or a supported metal / alloy catalyst. The metal may be any transition metal, or combination of one or more transition metals.

[0150] Suitable electrocatalyst that may be incorporated in the cathode 22 may, for example, comprise one or more of C, Pt, Fe, Co, Mo, and combinations thereof.

[0151] Suitable electrocatalyst that may be incorporated in the anode 19 may, for example, comprise one or more of Pt, Rh, Ir, Ru, Pd, Ni, and combinations thereof.

[0152] The cathode 22 and / or anode 19 may be porous. An example of a porous electrode is an electrode comprising an electrically conductive foam such as a metal foam. In some example embodiments, the cathode 22 and / or anode 19 comprises a layer of porous nickel (Ni) foam. The nickel foam layer may be free-standing or supported (e.g. by other components of a MEA).

[0153] Non-limiting examples of suitable materials to form the anode 19 include RuC>2 with carbon, Pt with carbon, Pt felt, Pt mesh, Au with carbon, Ni foam, Ni on carbon and carbon paper, MoOs on carbon paper, Mo(acac) on carbon paper, CoPc with carbon or carbon paper, and the like.

[0154] Non-limiting examples of suitable materials to form the cathode 22 include Ni foam, Ni with carbon, Pt with carbon, Pt felt, CoPc with carbon, RuC>2 with carbon, Fe- Ni with carbon, Cu with carbon, Cu-Ni with carbon, M0S2 with carbon or carbon paper, and the like.

[0155] In some embodiments, a suitable anolyte 54 is supplied to the anode chamber 18. In some embodiments, the anolyte 54 comprises the hydrogen-containingreactant 43.

[0156] In some embodiments, the anions of the anolyte 54 may for example comprise a monovalent anion such as fluoride (F'), chloride (Ch), bromide (Br), iodide (I-), nitrate (NO3‘), and / or a divalent anion such as sulfate (SC>42'), nitrite (NO2‘), acetate (CH3COO'), trifluoroacetate (CF3COO'), perchlorate (CIO4 ), chlorate (CIOs'), perchlorate (CIO4‘), sulfate (SO42'), bisulfate (HSO4‘), bromate (BrOs'), perbromate (BrO4‘), formate (HCOO-), propanoate (CsHsCOO-), lactate (CsHsOs'), trihalide acetate (CX3COO', where X=F, Cl, Br, I), triflate (CFsSOs'), and bistriflimide ([(CF3SO2)2N]'), etc.

[0157] The cations of the anolyte 54 may for example comprise a divalent cation such as an alkaline earth metal ions e.g., calcium (Ca2+), magnesium (Mg2+), and / or a transition metal ion (e.g., Fe2+), etc., and / or a monovalent cation such as an alkali metal, e.g., lithium (Li+), sodium (Na+), potassium (K+), rubidium (Rb+), and cesium (Cs+), ammonium (NH4+), etc.

[0158] In some embodiments, a reservoir containing the anolyte 54 and / or a metal-ion containing solids 74 is connected to supply the anolyte 54 and / or the metal-ion containing solids 74 to the anode chamber 18. The metal-ion containing solids 74 may be provided as an aqueous slurry of microparticles. The metal-ion containing solids 74 may react with the hydrogen ions 45 formed in the oxidation reaction 34 to yield metal ions 76. In some example embodiments, the metal-ion containing solids 74 comprise a silicate containing mineral. In such embodiments, the reacting of metal-ion containing solids 74 with the hydrogen ions 45 formed in the oxidation reaction 34 may additionally produce silica (SiO2) 75.

[0159] As illustrated in FIG. 3A, in some embodiments, a reservoir 120 is arranged to collect a mixture comprising one or more anode products 77 that may be removed from the anode chamber 18. The anode products 77 may comprise oxidation products 46 and / or products and / or byproducts formed in the reacting of the hydrogen ions 45 with the metal-ion containing solids 74 and / or other products and / or byproducts formed by reacting two or more of the anode products 77. In some embodiments, an inlet 121 of the reservoir 120 is fluidly connected to an outlet 68 of the anode chamber 18. The one or more anode products 77 comprise the metal ions 76. In some embodiments, the one or more anode products 77 comprise a saltformed by reacting the metal ions 76 with the sulfur-containing species with a sulfur atom in the higher oxidation state 51 and / or with unreacted sulfur-containing species with a sulfur atom in the lower oxidation state 47. In some embodiments in which the metal-ion containing solid 74 comprises a silicate mineral, the one or more anode products 77 additionally comprise silica (SiO2).

[0160] In some embodiments, the reservoir 120 is arranged to store the one or more anode products 77. In some embodiments, the reservoir 120 comprises one or more apparatuses configured to treat or process the one or more anode products 77. Suitable apparatuses include for example apparatuses configured to purify and / or concentrate the metal ions 76 and / or one or more salts comprising the metal ions 76 in the one or more anode products 77.

[0161] In some embodiments, an outlet 123 of the reservoir 120 is arranged to output the metal ions 76 and / or one or more salts comprising the metal ions 76. In some embodiments, the outlet 123 of the reservoir 120 is fluidly connected to an inlet 69 at the cathode chamber 20. The outlet 123 of the reservoir 120 may be arranged to output the untreated one or more anode products 77 and / or treated one or more anode products 77 to supply the metal ions 76 produced in the anode chamber 18 into the cathode chamber 20. The metal ions 76 participate in one or more reactions in the cathode chamber 20.

[0162] As illustrated in FIG. 3B, in some embodiments, the separator 24 is adapted to selectively permeate the metal ions 76 through the separator 24 from the anode chamber 18 into the cathode chamber 20. The metal ions 76 participate in one or more reactions in the cathode chamber 20.

[0163] In some embodiments, a reservoir containing a catholyte 56 is supplied to the cathode chamber 20.

[0164] In some embodiments, the anions of the catholyte 56 may comprise a divalent anion (e.g., sulfate ion (SC>42'), and / or a monovalent anion such as one or more of fluoride (F-), chloride (Cl-), bromide (Br), and iodide (I-), nitrite (NO2_), acetate (CH3COO‘), trifluoroacetate (CF3COO_), perchlorate (CIO4 ), chlorate (CIOs'), perchlorate (CIO4‘), sulfate (SO42'), bisulfate (HSO4‘), bromate (BrOs'), perbromate (BrO4‘), formate (HCOO'), propanoate (C2HsCOO'), lactate (CsHsOs'), trihalide acetate (CX3COO-, where X=F, Cl, Br, I), triflate (CF3SO3), and bistriflimide ([(CF3SO2)2N]-),etc.

[0165] The cations of the catholyte 56 may for example be a divalent cation such as an alkaline earth metal ions e.g., calcium (Ca2+), magnesium (Mg2+), or a transition metal ion (e.g., Fe2+), etc., or a monovalent cation such as an alkali metal, e.g., lithium (Li+), sodium (Na+), potassium (K+), rubidium (Rb+), and cesium (Cs+), ammonium (NH4+), etc.

[0166] In some embodiments, an inlet 86 is provided at the cathode chamber 20. The inlet 86 is fluidly connected to an outlet 84 of the source of the carbon dioxide feedstock 11 , adapted to discharge a flow of the carbon dioxide feedstock 85 into the cathode chamber 20. In some embodiments, an air distributor is fluidly connected to the inlet 86 at the cathode chamber 20. The air distributor may be configured to distribute a gaseous carbon dioxide feedstock 85 in the catholyte 56.

[0167] The carbon dioxide feedstock 85 reacts with the hydroxide ions 30 formed in the reduction reaction 36 and the metal ions 76 produced in the anode chamber 18 to yield metal carbonate 90.Example methods of converting metal-ion containing solids for carbon dioxide capture and storage which integrate the oxidation of sulfur-containing species

[0168] FIG. 4 is a flow chart illustrating the steps of a method 1500 of converting metal-ion containing solids for carbon dioxide capture and storage which integrate the oxidation of sulfur-containing species according to some embodiments of the invention.

[0169] In block 1502, an electrical current and / or potential is applied between an anode and a cathode.

[0170] In block 1503, a flow of a reduction reactant (e.g., a hydrogen-containing reactant) is supplied to the cathode chamber. The reduction reactant may be contained in the catholyte or may be separately supplied to the cathode.

[0171] In block 1506, the reduction reactant undergoes a reduction reaction at the cathode to produce hydroxide ions. The reduction reaction may comprise a hydrogen evolution reaction (HER).

[0172] In block 1508, a flow of a sulfur-containing species with a sulfur atom in a lower oxidation state is supplied to the anode chamber. A hydrogen-containingreactant such as water may be additionally supplied at the anode. The sulfur- containing species with a sulfur atom in the lower oxidation state may be contained in an anolyte (which may comprise the hydrogen-containing reactant) or may be separately supplied to the anode.

[0173] In block 1510, the sulfur-containing species with a sulfur atom in the lower oxidation state undergoes an oxidation reaction in the presence of the hydrogencontaining reactant at the anode to produce hydrogen ions and the sulfur-containing species with a sulfur atom in a higher oxidation state.

[0174] A flow of metal-ion containing solid is supplied to the anode chamber (block 1512). In some embodiments, the metal-ion containing solid is pre-treated before being supplied to the anode chamber. In some example embodiments, the pretreating comprises grinding the metal-ion containing solid, for example to an average diameter of less than about 1 mm. The ground metal-ion containing solid may be suspended into a liquid to form an aqueous slurry comprising microparticles. The metal-ion containing solid may be contained in the anolyte or be separately supplied to the anode chamber.

[0175] In block 1514, the metal-ion containing solid react with the hydrogen ions produced in the oxidation reaction to generate metal ions. In embodiments in which the metal-ion containing solid comprises silicate minerals, the reacting of the metalion containing solid with the hydrogen ions produces a silicon-containing by-product. In some embodiments, the silicon-containing by-product comprises silica (SiC>2).

[0176] In some embodiments of the invention, one or more anode products are removed from the anode chamber (block 1516A). The one or more anode products may comprise the metal ions and / or one or more salts comprising the metal ions.

[0177] The one or more anode products is optionally treated such as by purifying and / or concentrating the metal ions and / or one or more salts comprising the metal ions.

[0178] The untreated or treated anode products comprising the metal ions may be supplied into the cathode chamber (block 1520).

[0179] In some embodiments of the invention, the metal ions permeate through a separator from the anode chamber to the cathode chamber (block 1516B).

[0180] In block 1522, a flow of carbon dioxide feedstock is supplied into the cathodechamber. The carbon dioxide feedstock reacts with the metal ions produced in the anode chamber and the hydroxide ions formed in the reduction reaction to yield metal carbonates (block 1524).

[0181] Some aspects of the invention pertain to producing useful sulfur-containing compounds from the oxidation of a sulfur-containing species using the described system 1000, 1100. In such embodiments, the useful sulfur-containing compounds are produced by oxidizing, at the anode 18, a sulfur-containing species with a sulfur atom in a lower oxidation state 47 which produces a sulfur-containing species with a sulfur atom in a higher lower oxidation state 51. The sulfur-containing species with a sulfur atom in the higher lower oxidation state 51 may be removed from the cell 14. In some embodiments, a hydrogen-containing reactant is supplied to the cathode 22 to participate in a HER. However, this is not necessary. Other suitable reduction reactants may be supplied to the cathode 22 to participate in the reduction reaction 36.

[0182] In some embodiments, the sulfur-containing species with a sulfur atom in a higher oxidation state 51 comprises sulfate (SO42'). In some embodiments, the sulfur- containing species with a sulfur atom in a lower oxidation state 47 comprises sulfite (SO32’). In some embodiments, the system 1000, 1100 may be used to produce sulfuric acid (H2SO4). In some embodiments, the sulfate is removed from the anode chamber 18. One or more reactors may be connected downstream of the cell 14 to react the sulfate with hydrogen ions to yield sulfuric acid. In some embodiments, the oxidation of the sulfur -containing species with a sulfur atom the lower oxidation state 47 is performed in the presence of a hydrogen-containing reactant such as water to produce hydrogen ions 45 and the sulfur-containing species with a sulfur atom in the higher oxidation state 51. In such embodiments, the sulfuric acid may be formed in the anode chamber 18. The sulfuric acid may be removed from the anode chamber 18.

[0183] The method 1500 may be tuned to optimize one or more of current efficiency, applied electrical potential to achieve a desired current efficiency, product selectivity, efficiency and reaction rate of each of the electrochemical reactions and chemical reactions by adjusting one or more of:• conditions of the flow cell such as temperature, pH, pressure, etc.; and / or• characteristics of the separator such as the thickness, porosity, composition, etc.; and / or• characteristics of the anode and / or cathode electrodes such as the material and method of fabrication; and / or• nature of the cathode and / or anode catalyst;• additional catalysts present; and / or• the type of anolyte and catholyte; and / or• flow rate and / or composition and / or concentration of the sulfur-containing species with the lower oxidation state, reduction reactant, metal-ion containing solids, carbon dioxide feedstock, catholyte, and / or anolyte; and / or• in embodiments in which the metal ions are removed from the anode chamber before being supplied to the cathode chamber, rate at which the metal ions are removed from the cell;• in embodiments in which the metal ions are removed from the anode chamber before being supplied to the cathode chamber, purity and / or concentration of the metal ions being supplied to the cathode chamber;• rate at which metal carbonates are removed from the cell; etc.

[0184] In some embodiments, the electrical potential difference applied between cathode 22 and anode 19 to maintain the current density at a level of at least 25 mA cm-2to 100 mA cm-2does not exceed about 2 V and in some embodiments does not exceed about 1.4 V. In some embodiments, the electrical potential difference applied between cathode 22 and anode 19 to maintain the current density at a level of at least 200 mA cm-2to 1000 mA cm-2does not exceed about 6 V and in some embodiments does not exceed about 3 V.

[0185] In some embodiments, the electrolysis is operated at a temperature in the range of from 20°C to about 60°C. In some embodiments, the electrolysis is operated at a temperature less than about 60°C.

[0186] In some embodiments, the anolyte 54 and / or catholyte 56 are heated to a selected temperature before being supplied to the anode chamber 18 and cathode chamber 20 respectively. In some embodiments, the anolyte 54 and / or catholyte 56 are heated to a temperature in the range of from about 20 °C to about 60 °C.

[0187] In some example embodiments, the separator 24 comprises an ion exchangemembrane. The thickness of the ion exchange membrane may be in the range of from about 20 to about 200 m. In some embodiments, the separator 24 is a Nation™ 117 membrane. In some embodiments, the separator 24 is adapted to block passage of the metal ions 76. In some example embodiments, the separator 24 comprises a polyaniline (PANI)-coated cation exchange membrane.

[0188] In some embodiments, a flow rate at which the anolyte 54 and / or the catholyte 56 are supplied to the respective anode chamber 18 and cathode chamber 20 may for example be in the range of from about 30 to 800 mL min-1including any value or subrange therebetween for an electrode having a geometric surface area of 4 cm2. The flow rate may be scaled according to the area of the electrode. In some embodiments, a flow rate at which the anolyte 54 and / or the catholyte 56 are supplied to the respective anode chamber 18 and cathode chamber 20 is in the range of from about 50 to 350 mL min-1including any value or subrange therebetween for an electrode having a geometric surface area of 4 cm2.

[0189] In some embodiments, the concentration of the anolyte 54 and / or the catholyte 56 supplied to the respective anode chamber 18 and cathode chamber 20 is at least about 0.1 M, and in some embodiments, between 0.1 M and 1 M including any value or subrange therebetween.

[0190] In some embodiments, the concentration of the sulfur-containing species with a sulfur atom in the lower oxidation state is at least about 0.1 M, and in some embodiments, between 0.1 M and 2 M including any value or subrange therebetween.

[0191] In some embodiments, the pH within the cathode chamber 20 is maintained in the range of from about 9 to about 13 including any value and subrange therebetween, during electrolysis, and in some embodiments, between about 9 to about 11.

[0192] In some embodiments, the pH within the anode chamber 18 is maintained in the range of from about 1 to about 9 including any value and subrange therebetween, during electrolysis, and in some embodiments, less than about 4.

[0193] In some embodiments, a concentration of the metal-ion containing solid being supplied to the anode chamber is in the range of from about 0.01 to about 60 g / L, including any value or subrange therebetween.

[0194] In some example embodiments in which carbon dioxide feedstock comprises air, the concentration of the carbon dioxide supplied to the cathode chamber is up to about 400 ppm, including any value or subrange greater than 0 and between 0 to 400 ppm.

[0195] In some example embodiments in which the carbon dioxide feedstock comprises flue gas, the concentration of the carbon dioxide supplied to the cathode chamber is between about 3 to 40 vol%, and in some embodiments, between 5-20 vol%, including any value or subrange therebetween.

[0196] In some example embodiments in which carbon dioxide feedstock comprises air, a flow rate at which the carbon dioxide feedstock is supplied to the cathode chamber 20 may for example be up to about 2000 seem including any value or subrange therebetween, for an electrode having a geometric surface area of 4 cm2. The flow rate may be scaled according to the area of the electrode.

[0197] In some example embodiments in which carbon dioxide feedstock comprises flue gas, a flow rate at which the carbon dioxide feedstock is supplied to the cathode chamber 20 may for example be in the range of from about 50 to 200 seem, including any value or subrange therebetween, for an electrode having a geometric surface area of 4 cm2. The flow rate may be scaled according to the area of the electrode.

[0198] In summary, one example aspect of the invention provides particularly efficient systems and methods of converting metal-ion containing solids for carbon dioxide capture and storage which integrates the oxidation of sulfur-containing species such as but is not limited to sulfite (SOs2-).

[0199] In one example embodiment, sulfite is used as the sulfur-containing species with a sulfur atom in a lower oxidation state. Such an electrolyzer may also be referred to herein as a “sulfite electrolyzer”. However, it will be understood that other suitable sulfur-containing species with a sulfur atom in an oxidation state of less than +6 may be used. It will also be understood that the systems and methods described herein can convert other metal-ion containing solids to metal carbonates, and are not limited to the conversion of silicate minerals to metal carbonates and silica (SiC>2).

[0200] The example sulfite electrolyzer comprises two chambers. The sulfite electrolyzer comprises an anode chamber and a cathode chamber. A cation exchange membrane separates the anode chamber from the cathode chamber. Thesulfite electrolyzer may comprise a zero-gap configuration having the anode, cation exchange membrane and cathode being pressed between two spaced flow plates.

[0201] NaCI solution is supplied to the cathode chamber as the catholyte, and Na2SC>3 solution is supplied to the anode chamber as the anolyte. The anolyte (Na2SC>3 solution) comprises the sulfur-containing species with a sulfur atom in the lower oxidation state and the hydrogen-containing reactant.

[0202] The sulfite (SOs2-) participates in an oxidation reaction at the anode to produce hydrogen ions (H+) and sulfate (SOU2-)- Such an oxidation reaction may be referred to as the “SO3OR”.

[0203] A slurry of silicate containing mineral (e.g., Mg2SiC>4) may be supplied to the anode chamber. The hydrogen ions generated at the anode react with the silicate (e.g., Mg2SiO4) to release metal ions (e.g., Mg2+), and silica (SiC>2). Anode products comprising the metal ions (e.g., Mg2+) which may additionally comprise the sulfate (SO42’) are removed from the anode chamber.

[0204] A hydrogen evolution reaction (HER) may occur at the cathode. The HER may convert the reduction reactant, e.g., water, into hydroxide ions and hydrogen gas.

[0205] A solution comprising the anode products which comprise the metal ions (e.g., Mg2+)and the sulfate (SC>42') which may form a salt (e.g., MgSC>4) is supplied to the cathode chamber.

[0206] A feedstock comprising carbon dioxide is supplied into the cathode chamber. The carbon dioxide reacts with the hydroxide ions and the metal ions from the anode products (e.g., Mg2+) to yield metal carbonate (e.g., MgCOs).Systems and methods for converting metal-ion containing solids for carbon dioxide capture and storage using a three-chamber cell

[0207] Aspects of the invention relate to systems and methods of converting metalion containing solids for carbon dioxide capture and storage using a three-chamber cell. FIG. 5 is a schematic diagram which illustrates an example system 2000 for converting metal-ion containing solids to metal carbonates, and additionally produces silica. The illustrated embodiment shows the production of metal carbonate and silica (or silicon dioxide, SiC>2). In such embodiments, the metal-ion containing solid comprises a silicate containing compound. However, the system 2000 may beoperable to produce other one or more compounds. The produced one or more compounds may depend on the composition of the metal-ion containing solids. The system 2000 comprises an electrochemical cell 14 and a source of carbon dioxide feedstock 11 in fluid communication with the cell 14 such that the carbon dioxide feedstock 11 is supplied into the cell 10 for reaction to yield metal carbonates 90.

[0208] One application of this system and method is in carbon capture and storage. The system 2000 integrates all of the steps necessary for carbon capture and storage in a single three-chamber weathering electrolyzer.Example system of converting metal-ion containing solids for carbon capture and storage using a three-chamber cell

[0209] Referring to FIG. 5, the cell 14 comprises an anode chamber 18, a cathode chamber 20, and a chemical chamber 26. A cathode 22 is exposed to the cathode chamber 20. An anode 19 is exposed to the anode chamber 18. A separator 24 separates the chemical chamber 26 and the cathode chamber 20. A bipolar membrane 28 separates the anode chamber 18 and the chemical chamber 26. A cation exchange layer 31 of the bipolar membrane 28 is arranged to face the chemical chamber 26. An anion exchange layer 33 of the bipolar membrane 28 is arranged to face the anode chamber 18. The bipolar membrane 28 is adapted to dissociate water molecules into hydroxide ions 27 and hydrogen ions 29. The hydrogen ions 29 may permeate through the cation exchange layer 31 into the chemical chamber 26. The hydroxide ions 27 may permeate through the anion exchange layer 33 into the anode chamber 18.

[0210] The separator 24 is adapted to selectively allow passage of the metal ion in the metal-ion containing solids that is fed to the system 2000 for processing. In some example embodiments, the separator 24 is adapted to selectively allow passage of divalent cations, such as but are not limited to calcium ions (Ca2+) and magnesium ions (Mg2+).

[0211] In some example embodiments, the separator 24 comprises an ion exchange membrane such as a cation exchange membrane. The separator 24 may however be any other suitable membrane which is adapted to allow passage of ions therethrough. In some embodiments, the separator 24 comprises a microporous polymermembrane.

[0212] A power source 32 is connected to apply an electrical potential difference between the cathode 22 and the anode 19. A negative electrical charge is applied to the cathode 22. A positive electrical charge is applied to the anode 19.

[0213] The power source may be configured to maintain a desired electric current between the cathode 22 and the anode 19 and / or to maintain a potential difference between the cathode 22 and the anode 19 at a desired level or in a desired range.

[0214] An oxidation reaction 34 takes place at the anode 19. A reduction reaction 36 takes place at the cathode 22.

[0215] A reservoir comprising a hydrogen-containing reactant 38 may be fluidly connected to supply the hydrogen-containing reactant 38 to the cathode chamber 20. In some embodiments, the hydrogen-containing reactant 38 participates in the reduction reaction 36 to generate hydroxide ions 30.

[0216] In some embodiments, the reduction reaction comprises a hydrogen evolution reaction (HER). In such embodiments, the hydrogen-containing reactant 38 comprises water.

[0217] An oxidation reactant 44 participates in the oxidation reaction 34 to form an oxidation product 46. In some embodiments, the oxidation reaction 34 comprises an oxygen evolution reduction (OER). In some embodiments, the oxidation reactant 44 comprises the hydroxide ions 27 formed at the bipolar membrane 28. In some embodiments, the oxidation reactant 44 comprises a solution containing hydroxide ions (OH-). The oxidation reactant 44 need not comprise hydroxide ions. Any suitable reactant which may be oxidized to form an oxidation product.

[0218] The cathode 22 may comprise any materials suitable for use as an electrode. Such material may, for example, comprise a catalyst suitable for driving a hydrogen evolution reaction (HER).

[0219] The anode 19 may comprise any materials suitable for use as an electrode. Such material may comprise a catalyst suitable for driving an oxygen evolution reaction (OER).

[0220] The cathode 22 and / or anode 19 may be a gas diffusion electrode.

[0221] The cathode 22 and / or anode 19 may be made of one or more metal, alloy, oxides, hydroxides, chalcogenides, phosphides, nitrides, or a supportedmetal / alloy / oxides / hydroxides / chalcogenides / phosphides / nitrides catalyst. The metal may be any transition metal, or combination of one or more transition metals. Suitable electrocatalyst that may be incorporated in the cathode 22 may, for example, comprise one or more of C, Pt, Ni, Fe, Co, Mo, W, and combinations thereof. Suitable electrocatalyst that may be incorporated in the anode 19 may, for example, comprise one or more of Pt, Rh, Ir, Ru, Pd, Ni, Fe, Co and combinations thereof.

[0222] The cathode 22 and / or anode 19 may be porous. An example of a porous electrode is an electrode comprising an electrically conductive foam or mesh or paper such as a metal foam or a carbon paper. In some example embodiments, the cathode 22 and / or anode 19 comprises a layer of porous nickel (Ni) foam. The nickel foam layer may be free-standing or supported (e.g. by other components of a membrane electrode assembly).

[0223] In some embodiments, a suitable anolyte 54 is supplied to the anode chamber 18. In some embodiments, the anolyte 54 comprises a base. In some example embodiments, the anolyte 54 comprises a solution containing hydroxide ions (OH-) such as a water-soluble alkali or alkaline earth base (e.g., NH4OH, LiOH, NaOH, KOH, RbOH, CsOH, Ba(OH)2). In some embodiments, the anolyte 54 comprises the oxidation reactant 44.

[0224] A catholyte 56 is supplied to the cathode chamber 20. In some embodiments, the cations of the catholyte 56 are monovalent. The cations of the catholyte 56 may for example comprise one or more alkali metal ions such as lithium (Li+), sodium (Na+), potassium (K+), rubidium (Rb+), and cesium (Cs+), ammonium (NH4+), etc. In some embodiments, the anions of the catholyte 56 are monovalent and / or divalent. The anions of the catholyte 56 may for example comprise one or more of fluoride (F-), chloride (Cl-), bromide (Br), and iodide (I-), nitrate (NO3_), nitrite (NO2, acetate (CH3COO'), perchlorate (CIO4 ), chlorate (CIOs'), sulfate (SO42'), bromate (BrOs'), perbromate (BrO4‘), formate (HCOO'), propanoate (C2HsCOO'), lactate (CsHsOs'), trihalide acetate (CX3COO', where X=F, Cl, Br, I), triflate (CFsSOs'), and bistriflimide ([(CF3SO2)2N]-), and / or sulfate (SO42'), etc.

[0225] In some embodiments, a reservoir comprising one or more amino acids and / or amino acid salts is connected to supply the one or more amino acid and / or amino acid salt into the cathode chamber 20. In some embodiments, the amino acid and / oramino acid salt is contained in the catholyte 56.

[0226] In some embodiments, the amino acid comprise one or more alanine, arginine, asparagine, aspartate, citrulline, cysteine, cystine, glutamine, glutamate, glycine, histidine, hydroxyproline, isoleucine, leucine, lysine, methionine, ornithine, phenylalanine, proline, serine, taurine, threonine, tryptophan, tyrosine, valine, y- aminobutanoic acid, etc.. The amino acid salt comprises one or more salts of the above listed amino acids such as a monovalent cation (e.g., Li+, Na+, K+, N , Rb+, Cs+) salt of the amino acids. The addition of amino acids and / or amino acid salts may promote efficient carbon dioxide capture and mineralization to carbonization solids.

[0227] A chemolyte 60 is supplied to the chemical chamber 26. In some embodiments, the chemolyte 60 is derived from a pH-neutral aqueous solution. In some embodiments, the chemolyte 60 has a pH in the range of from about 6 to about 8. In some embodiments, the cations of the chemolyte 60 are monovalent and / or divalent. The cations of the chemolyte 60 may for example comprise one or more alkali metal ions such as lithium (Li+), sodium (Na+), potassium (K+), rubidium (Rb+), and cesium (Cs+), ammonium (NH4+), and / or an alkaline earth metal ion such as calcium (Ca2+) and / or magnesium (Mg2+). In some embodiments, the anions of the chemolyte 60 are monovalent. The anions of the chemolyte 60 may for example comprise one or more of fluoride (F-), chloride (Cl-), bromide (Br), and iodide (I-), nitrate (NO3_), nitrite (NCh , acetate (CH3COO'), trifluoroacetate (CF3COO'), perchlorate (CIO4 ), chlorate (CIOs'), perchlorate (CIO4'), sulfate (SO42'), bisulfate (HSO4‘), cyanide (CN'), bromate (BrOs'), perbromate (BrO4‘), formate(HCOO'), propanoate (C2HsCOO'), lactate (CsHsOs'), trihalide acetate (CX3COO', where X=F, Cl, Br, I), triflate (CF3SO3), and bistriflimide ([(CF3SO2)2N]').

[0228] In some embodiments, a reservoir containing the chemolyte 60 and / or the metal-ion containing solids 74 is connected to supply the chemolyte 60 and / or the metal-ion containing solids 74 to the chemical chamber 26. The metal-ion containing solids 74 may be provided as an aqueous slurry of microparticles. The metal-ion containing solids 74 may react with the hydrogen ions 29 formed at the bipolar membrane 28 to yield metal ions 76.

[0229] In some example embodiments, the metal-ion containing solids 74 comprise a silicate containing mineral. In such embodiments, the reacting of the metal-ioncontaining solids 74 with the hydrogen ions 29 may additionally produce silica (SiC>2) 75..

[0230] The separator 24 may be adapted to selectively pass the metal ions 76 from the chemical chamber 26 to the cathode chamber 20 for reaction to yield metal carbonates.

[0231] In some embodiments, a first inlet 86 is provided at the cathode chamber 20. The first inlet 86 is fluidly connected to an outlet 84 of the source of the carbon dioxide feedstock 11 , adapted to discharge a flow of the carbon dioxide feedstock 85 into the cathode chamber 20. In some embodiments, an air distributor is fluidly connected to the first inlet 86 at the cathode chamber 20. The air distributor may be configured to distribute a gaseous carbon dioxide feedstock 85 in the catholyte 56.

[0232] The carbon dioxide feedstock 85 reacts with the hydroxide ions 30 formed in the reduction reaction 36 and the metal ions 76 produced in the chemical chamber 26 to yield metal carbonate 90.

[0233] FIG. 6 is a flow chart illustrating the steps of a method 2500 of converting metal-ion containing solids for carbon dioxide capture and storage using a three- chamber cell.

[0234] In block 2502, an electrical current and / or potential is applied between an anode and a cathode.

[0235] In block 2503, water is electrochemically dissociated at a bipolar membrane to form hydrogen ions and hydroxide ions. The hydrogen ions may permeate through a cation exchange layer of the bipolar membrane to enter a chemical chamber. The hydroxide ions may permeate through an anion exchange layer of the bipolar membrane to enter an anode chamber.

[0236] In block 2504, an oxidation reactant participates in an oxidation reaction at the anode to form an oxidation product. In some embodiments, the hydroxide ions formed at the bipolar membrane undergoes the oxidation reaction at the anode to form the oxidation product. In some embodiments, an anolyte comprising the oxidation reactant is supplied to the anode to participate in an oxidation reaction to form the oxidation product.

[0237] In block 2506, a hydrogen-containing reactant such as water is supplied to the cathode. The hydrogen-containing reactant undergoes a reduction reaction at thecathode to produce hydroxide ions (block 2507). A catholyte containing the hydrogencontaining reactant may be supplied to the cathode chamber. The catholyte and the hydrogen-containing reactant may be separately supplied to the cathode chamber.

[0238] In block 2508, a metal-ion containing solid may be supplied to the chemical chamber. A chemolyte containing the metal-ion containing solid may be supplied to the chemical chamber. The chemolyte and the metal-ion containing solid may be separately supplied to chemical chamber.

[0239] In block 2510, the metal-ion containing solids react with the hydrogen ions produced at the bipolar membrane to form metal ions. In some embodiments, the reacting of the metal-ion containing solids with the hydrogen ions additionally produces silica (SiC>2).

[0240] In block 2512, the metal ions permeate through a separator to enter the cathode chamber.

[0241] In block 2514, a flow of carbon dioxide feedstock is supplied into the cathode chamber. The carbon dioxide feedstock reacts with the metal ions formed at the chemical chamber and the hydroxide ions formed in the reduction reaction to yield metal carbonates (block 2516).

[0242] The method 2500 may be tuned to optimize one or more of current efficiency, applied electrical potential to achieve a desired current efficiency, product selectivity, efficiency and reaction rate of each of the reactions by adjusting one or more of:• conditions of the flow cell such as temperature, pH, pressure, etc.; and / or• characteristics of the bipolar membrane and / or the separator such as the thickness, porosity, composition, etc.; and / or• characteristics of the anode and / or cathode electrodes such as the material and method of fabrication; and / or• nature of the cathode and / or anode catalyst;• additional catalysts present; and / or• the type of anolyte, chemolyte, and catholyte; and / or• flow rate and / or composition and / or concentration of the oxidation reactant, reduction reactant, metal-ion containing solids, carbon dioxide feedstock, catholyte, chemolyte and / or anolyte; and / or• rate at which metal carbonates are removed from the cell;• distance across the chemical chamber between the bipolar membrane and the separator; etc.• etc.

[0243] In some embodiments, the electrolysis is operated at a temperature in the range of from 25 °C to about 60 °C. In some embodiments, the electrolysis is operated at a temperature less than about 60 °C.

[0244] In some embodiments, the anolyte 54 and / or catholyte 56 are heated to a selected temperature before being supplied to the anode chamber 18 and cathode chamber 20 respectively. In some embodiments, the anolyte 54 and / or catholyte 56 are heated to a temperature in the range of from about 20 °C to about 60 °C.

[0245] In some example embodiments, the separator 24 comprises an ion exchange membrane. The thickness of the ion exchange membrane may be in the range of from about 20 to about 200 pm. In some embodiments, the separator 24 is a Nation™ 117 membrane.

[0246] In some embodiments, the thickness of bipolar membrane 28 is in the range of from about 25 to about 250 pm. In some embodiments, bipolar membrane 28 is a product commercially available under the product name Fumasep™ FBM. In some embodiments, biopolar membrane 28 is fabricated by combining a cation exchange layer (such as a Nation™ 211 membrane) and an anion exchange layer (such as an Aemion™ CNN-8-25X membrane).

[0247] In some embodiments, a flow rate at which the anolyte 54, the chemolyte 60, and / or the catholyte 56 are supplied to the respective anode chamber 18, chemical chamber 26, and cathode chamber 20 may for example be in the range of from about 30 to 800 mL min-1including any value or subrange therebetween for an electrode having a geometric surface area of 4 cm2. The flow rate may be scaled according to the area of the electrode. In some embodiments, a flow rate at which the anolyte 54, the chemolyte 60, and / or the catholyte 56 are supplied to the respective anode chamber 18, chemical chamber 26, and cathode chamber 20 is in the range of from about 50 to 350 mL min-1including any value or subrange therebetween for an electrode having a geometric surface area of 4 cm2.

[0248] In some embodiments, the concentration of the anolyte 54, the chemolyte 60, and / or the catholyte 56, supplied to the respective anode chamber 18, chemicalchamber 26, and cathode chamber 20 is up to about 14.0 M, including any value or subrange greater than 0 and between 0 and 14 M.

[0249] In some embodiments, the concentration of the amino acid and / or amino acid salt contained in a solution such as the catholyte 56 is up to about 1 M, including any value or subrange between 0 and 1 M. In some embodiments, the percentage of amino acid salt in total amino acid species contained in a solution such as the catholyte 56 is up to 100 mol%, including any value or subrange between 0 and 100 mol%.

[0250] In some embodiments, the pH within the chemical chamber is maintained in the range of from about 1 to about 10, including any value and subrange therebetween, during electrolysis, and in some embodiments, less than about 4.

[0251] In some embodiments, the pH within the cathode chamber is maintained in the range of from about 7 to 13, including any value and subrange therebetween, during electrolysis.

[0252] In some embodiments, a concentration of the metal-ion containing solid being supplied to the anode chamber is in the range of from about 1 g / L to about 100 g / L, including any value or subrange therebetween.

[0253] In some example embodiments in which carbon dioxide feedstock comprises air, the concentration of the carbon dioxide supplied to the cathode chamber is up to about 400 ppm, including any value or subrange greater than 0 and between 0 to 400 ppm.

[0254] In some example embodiments in which the carbon dioxide feedstock comprises flue gas, the concentration of the carbon dioxide supplied to the cathode chamber is between about 3 to 40 vol%, and in some embodiments, between 5-20 vol%, including any value or subrange therebetween.

[0255] In some example embodiments in which carbon dioxide feedstock comprises air, a flow rate at which the carbon dioxide feedstock is supplied to the cathode chamber 20 may for example be up to about 2000 seem including any value or subrange therebetween, for an electrode having a geometric surface area of 4 cm2. The flow rate may be scaled according to the area of the electrode.

[0256] In some example embodiments in which carbon dioxide feedstock comprises flue gas, a flow rate at which the carbon dioxide feedstock is supplied to the cathodechamber 20 may for example be in the range of from about 50 to 200 seem, including any value or subrange therebetween, for an electrode having a geometric surface area of 4 cm2. The flow rate may be scaled according to the area of the electrode.

[0257] In summary, one example aspect of the invention provides systems and methods of converting metal-ion containing solids for carbon dioxide capture and storage using a three-chamber cell. This conversion may involve the conversion of a silicate mineral (e.g., CaSiOs) to calcium carbonate (CaCOs) and silica (SiC>2). It will however be understood that the systems and methods described herein may be used to convert any suitable metal-ion containing solids to metal carbonates.

[0258] One aspect of the invention provides a continuous flow electrochemical reactor configured for capturing and storing carbon dioxide in the form of inert carbonate minerals. Such electrolyzer may also be referred to herein as a “weathering electrolyzer”.

[0259] The example weathering electrolyzer comprises three chambers. The weathering electrolyzer comprises an anode chamber, a cathode chamber, a chemical chamber between the anode and cathode chamber. A bipolar membrane separates the anode chamber and the chemical chamber. A cation exchange membrane separates the chemical chamber from the cathode chamber.

[0260] An anolyte (e.g., KOH) and catholyte (e.g., KOI) are supplied to the respective anode and cathode chamber. A slurry of metal-ion containing solid (e.g., CaSiOs) contained in a chemolyte (e.g., CaC solution) is supplied to the chemical chamber.

[0261] Electrochemical dissociation of water at the bipolar membrane generates hydrogen ions and hydroxide ions.

[0262] The hydrogen ions are supplied to the chemical chamber to facilitate dissolution of the metal-ion containing solid (e.g., CaSiOs) into metal ions (e.g., Ca2+), and additionally producing silica (SiC>2). The metal ions (e.g., Ca2+) transport through a Ca2+-selective cation exchange membrane into the cathode chamber.

[0263] Water is reduced at the cathode to produce hydroxide ions. The hydroxide ions and the metal ions (e.g., Ca2+) react with an external supply of carbon dioxide in the cathode chamber to yield metal carbonates (e.g., CaCOs).Systems and methods for continuous conversion of metal-ion containing solids forcarbon dioxide capture and storageExample system of continuous conversion of metal-ion containing solids for carbon dioxide capture and storage

[0264] Some aspects of the invention pertain to continuous conversion of metal-ion containing solids. The continuous conversion may be performed in a two-chamber cell, or in a three-chamber cell. FIGs. 7A and 7B illustrate systems 3000, 3100 according to some example embodiments of the invention. The systems 3000, 3100 comprise a cell 14, an extractor 12 configured to extract metal ions from a metal-ion containing solid, and a carbon capture and storage unit 16 configured to separate one or more products. The cell 14, extractor 12 and the carbon capture and storage unit 16 are connected in fluid communication.

[0265] Referring to FIGS . 7A and 7B, the systems 3000, 3100 each comprises an electrochemical cell 14. The cell 14 comprises an anode chamber 18 and a cathode chamber 20. A cathode 22 is exposed to the cathode chamber 20. An anode 19 is exposed to the anode chamber 18.

[0266] In some embodiments, the cell 14 comprises two chambers. In such embodiments, a separator 24 separates the anode chamber 18 and the cathode chamber 20.

[0267] In some embodiments, the cell 14 comprises three chambers. In such embodiments, a chemical chamber 26 is between the anode chamber 18 and the cathode chamber 20. A bipolar membrane 28 separates the anode chamber 18 and the chemical chamber 26. The bipolar membrane 28 is adapted to dissociate water molecules into hydroxide ions 27 and hydrogen ions 29. The hydrogen ions 29 may permeate through a cation exchange layer 31 into the chemical chamber 26. A separator 24 separates the chemical chamber 20 and the cathode chamber 20.

[0268] In some embodiments, the separator 24 is adapted to selectively allow passage of the metal ion in the metal ion-containing solids that is fed to the system 3000, 3100 for processing. In some example embodiments, the separator 24 is adapted to selectively allow the passage of divalent ions, such as calcium or magnesium ions.

[0269] In some embodiments, the separator 24 comprises an ion exchange membrane such as a cation exchange membrane. In some embodiments, theseparator 24 comprises a microporous membrane.

[0270] A power source 32 is connected to apply an electrical potential difference between the cathode 22 and the anode 19. A negative electrical charge is applied to the cathode 22. A positive electrical charge is applied to the anode 19.The power source may be configured to maintain a desired electric current between the cathode 22 and the anode 19 and / or to maintain a potential difference between the cathode 22 and the anode 19 at a desired level or in a desired range.

[0271] An oxidation reaction 34 takes place at the anode 19. A reduction reaction 36 takes place at the cathode 22.

[0272] In some embodiments, the reduction reaction comprises a hydrogen evolution reaction (HER). In such embodiments, the hydrogen-containing reactant 38 comprises water.

[0273] An oxidation reactant 44 participates in the oxidation reaction 34 to form an oxidation product 46. In some embodiments, the oxidation reaction 34 comprises an oxygen evolution reduction (OER).

[0274] In some embodiments, the oxidation reactant 44 comprises a hydrogencontaining reactant 43. In some embodiments, a reservoir containing the hydrogencontaining reactant 43 may be fluidly connected to supply the hydrogen-containing reactant 43 to the anode 19. In some embodiments, the oxidation product 46 comprises hydrogen ions 45.

[0275] In some embodiments, the oxidation reactant 44 comprises a solution containing hydroxide ions (OH-). The oxidation product 46 may comprise oxygen gas (O2) and water molecules.

[0276] The cathode 22 may comprise any materials suitable for use as an electrode. Such material may, for example comprise a catalyst suitable for driving a hydrogen evolution reaction (HER).

[0277] The anode 19 may comprise any materials suitable for use as an electrode. Such material may comprise a catalyst suitable for driving an oxygen evolution reaction (OER).

[0278] The cathode 22 and / or anode 19 may be a gas diffusion electrode.

[0279] The cathode 22 and / or anode 19 may be made of one or more metal, alloy or a supported metal / alloy catalyst. The metal may be any transition metal, orcombination of one or more transition metals. Suitable electrocatalyst that may be incorporated in the cathode 22 may, for example, comprise one or more of C, Pt, Fe, Co, Mo, and combinations thereof. Suitable electrocatalyst that may be incorporated in the anode 19 may, for example, comprise one or more of Pt, Rh, Ir, Ru, Pd, Ni, and combinations thereof.

[0280] The cathode 22 and / or anode 19 may be porous. An example of a porous electrode is an electrode comprising an electrically conductive foam such as a metal foam. In some example embodiments, the cathode 22 and / or anode 19 comprises a layer of porous nickel (Ni) foam. The nickel foam layer may be free-standing or supported (e.g. by other components of a membrane electrode assembly).

[0281] In some embodiments, a suitable anolyte 54 is supplied to the anode chamber 18. In some embodiments, the anolyte 54 comprises a hydrogen-containing reactant 43 such as water. In some embodiments, the anolyte 54 comprises a base. In some example embodiments, the anolyte 54 comprises a solution containing hydroxide ions (OH-). In some embodiments, the anolyte 54 comprises the oxidation reactant 44.

[0282] In some embodiments, the anolyte 54 comprises a pH-neutral aqueous solution. In some embodiments, the anolyte 54 has a pH in the range of from about 6 to about 8. In some embodiments, the anions and / or cations of the anolyte 54 are monovalent. The anions of the anolyte 54 may for example comprise one or more of fluoride (F'), chloride (Cl-), bromide (Br), and iodide (I-), hydroxide (OH-), nitrate (NO3-), nitrite (NCh , bicarbonate (HCOs'), acetate (CHsCOO'), trifluoroacetate (CFsCOO-), perchlorate (CIO4 ), chlorate (CIOs'), hypochlorite (CIO'), bisulfate (HSO4 ), cyanide (ON'), and hydride (H). The cations of the anolyte 54 may for example comprise one or more alkali metal ions such as lithium (Li+), sodium (Na+), potassium (K+), rubidium (Rb+), and cesium (Cs+), hydrogen (H+), ammonium (NH4+), hydronium (HsO+), tetramethylammonium ((CHs)4N+), tetraethylammonium ((C2HS)4N+), trimethylammonium ((CHs)3H+), silver (Ag+), and thallium (Tl+).

[0283] A catholyte 56 is supplied to the cathode chamber 20. In embodiments in which a chemical chamber 26 is present, a chemolyte 60 is supplied to the chemical chamber 26.

[0284] In some embodiments, the catholyte 56 and / or chemolyte 60 are derived from a pH-neutral aqueous solution. In some embodiments, the catholyte 56 and / orchemolyte 60 has a pH in the range of from about 6 to about 8. In some embodiments, the anions and / or cations of the catholyte 56 and / or chemolyte 60 are monovalent. The anions of the catholyte 56 and / or chemolyte 60 may for example comprise one or more of fluoride (F'), chloride (Cl-), bromide (Br), and iodide (I-), hydroxide (OH-), nitrate (NOs'), nitrite (NCh-), bicarbonate (HCOs'), acetate (CHsCOO-), trifluoroacetate (CFsCOO'), perchlorate (CIO4 ), chlorate (CIOs'), hypochlorite (CIO-), bisulfate (HSO4'), cyanide (CN_), and hydride (H). The cations of the catholyte 56 and / or chemolyte 60 may for example comprise one or more alkali metal ions such as lithium (Li+), sodium (Na+), potassium (K+), rubidium (Rb+), and cesium (Cs+), hydrogen (H+), ammonium (NH4+), hydronium (HsO+), tetramethylammonium ((CHs)4N+), tetraethylammonium ((C2Hs)4N+), trimethylammonium ((CHs)3H+), silver (Ag+), and thallium (Tl+).

[0285] In some embodiments, a first outlet 68 is provided at the cell 14. The first outlet 68 is adapted to discharge a flow of electrolyte 64 out the cell 14. The first outlet 68 may be fluidly connected to an inlet 70 of the extractor 12. The electrolyte 64 discharged from the cell 14 may be caused to flow from the cell 14 to the extractor 12. The electrolyte 64 may be anolyte 54 and / or catholyte 56, and / or chemolyte 60 that has been acidified by the hydrogen ions that are formed at the bipolar membrane 28 and / or in the oxidation reaction 34 at the anode 19.

[0286] In some embodiments, the first outlet 68 is arranged at the anode chamber 18. In such embodiments, the outlet 68 is arranged to discharge a flow of the electrolyte 64 out of the anode chamber 18 into the extractor 12. In such embodiments, the electrolyte 64 may comprise the anolyte 54 that has been acidified by the hydrogen ions that are formed in the oxidation reaction 34 at the anode 19.

[0287] In some embodiments, the first outlet 68 is arranged at the chemical chamber 26. In such embodiments, the outlet 68 is arranged to discharge a flow of the electrolyte 64 out of the chemical chamber 26 into the extractor 12. In such embodiments, the electrolyte 64 may comprise the chemolyte 60 that has been acidified by the hydrogen ions that are formed at the bipolar membrane 28.

[0288] In some embodiments, a reservoir containing metal ion-containing solids 74 is connected to supply the metal-ion containing solids 74 to the extractor 12. The extractor 12 is configured to extract metal ions 76 from the metal ion-containing solids74. The metal ions 76 may be dissolved in the electrolyte 64 supplied into the extractor 12, thereby forming a metal-ion-enriched electrolyte 82. An outlet 83 is provided at the extractor 12 for output of the metal-ion-enriched electrolyte 82 out of the extractor 12.

[0289] In some embodiments, the extracting of the metal ions 76 from the metal ioncontaining solids 74 additionally produces silica. In such embodiments, the metal ioncontaining solids 74 may comprise a silicate containing mineral.

[0290] In some embodiments, the outlet 83 of the extractor 12 is fluidly connected to a first inlet 86 of the cell 14.

[0291] In some embodiments, the first inlet 86 is arranged at the anode chamber 18. In such embodiments, the metal-ion-enriched electrolyte 82 is directed to flow out of the extractor 12 to the anode chamber 18. The metal-ion-enriched electrolyte 82 provides a source of the metal ions 76 to the anode chamber 18 for passage through the separator 24 to the cathode chamber 20.

[0292] In some embodiments, the first inlet 86 arranged at the chemical chamber 26. In such embodiments, the metal-ion-enriched electrolyte 82 is directed to flow out of the extractor 12 to the chemical chamber 26. The metal-ion-enriched electrolyte 82 provides a source of the metal ions 76 to the chemical chamber 26 for passage through the separator 24 to the cathode chamber 20.

[0293] The extractor 12 can be any suitable apparatus configured to dissolute one or more components in a liquid solvent. The one or more components may comprise a solid compound, or a mixture comprising one or more solid components. In some embodiments, the extractor 12 is a solid-liquid extractor. A filter is typically arranged in the extractor 12 adapted to separate the solid component from the liquid component. The solid component retains on the filter while the liquid component is caused to flow out of the extractor 12.

[0294] In some embodiments, a second outlet 92 is provided at the cell 14. The second outlet 92 is adapted to discharge a flow of the hydroxide ions 30 and metal ions 76 out of the cell 14. The second outlet 92 may be adapted to additionally discharge a flow of the electrolyte 65 (one or more of anolyte 54, catholyte 56, and chemolyte 60) out the cell 14. The concentration of the metal ions 76 in the flow of the electrolyte that is caused to flow out of the cell 14 at the second outlet 92 is less thanor equal to the concentration of the metal ions 76 in the metal-ion-enriched electrolyte 82. In some embodiments, the second outlet 92 is arranged at the cathode chamber 20.

[0295] The second outlet 92 may be fluidly connected to an inlet 94 of the carbon capture and storage unit 16 arranged for output of the hydroxide ions 30 and metal ions 76 and in some embodiments, metal hydroxides formed by reaction between the hydroxide ions 30 and the metal ions 76, and the electrolyte 65 from the cell 14 to the carbon capture and storage unit 16.

[0296] A source of carbon dioxide 11 is fluidly connected to the carbon capture and storage unit 16. An outlet 84 of the source of the carbon dioxide 11 may be fluidly connected to an inlet 99 of the carbon capture and storage unit 16 adapted to discharge a supply of a feedstock comprising carbon dioxide 85 into the carbon capture and storage unit 16. In some embodiments, an air distributor is fluidly connected to the inlet 99 at the carbon capture and storage unit 16. The air distributor may be configured to distribute a gaseous carbon dioxide feedstock 85 in the carbon capture and storage unit 16. The hydroxide ions 30 and metal ions 76 output from the cell 14 may react with the feedstock comprising carbon dioxide 85 in the carbon capture and storage unit 16 to yield metal carbonate 90.

[0297] In some embodiments, the carbon capture and storage unit 16 is configured to separate the metal carbonate 90 from a liquid 100. The liquid 100 may comprise the electrolyte 65. The liquid 100 is free or substantially free of metal carbonate 90.

[0298] The carbon capture and storage unit 16 can be any suitable apparatus configured to separate desired one or more components, here metal carbonates, from other components in a mixture. In some example embodiments, the carbon capture and storage unit 16 comprises a filter. The filter is made of a porous material. The filter is adapted to separate components in a mixture by retaining one or more components on the filter, and allowing one or more other components to pass through the filter.

[0299] A second inlet 96 may be provided at the cell 14. The second inlet 96 may be fluidly connected to an outlet 98 of the carbon capture and storage unit 16. The liquid 100 may be caused to flow out of the carbon capture and storage unit 16 through the outlet 98 into the cell 14 through the second inlet 96.

[0300] In some embodiments, the second inlet 96 is arranged at the cathode chamber 20. In such embodiments, the outlet 98 of the carbon capture and storage unit 16 is fluidly connected to direct a flow of the liquid 100 to the cathode chamber 20.

[0301] In some embodiments, the carbon capture and storage unit 16 is adapted to discharge a flow of a carbon dioxide depleted gas through an outlet 104.

[0302] One or more gas-liquid separators 102 may be provided between the cell 14 and the extractor 12 and / or carbon capture and storage unit 16 configured to separate one or more gasses from the electrolyte 64, 65 before supplying the electrolyte 64, 65 into the extractor 12 and the carbon capture and storage unit 16 respectively. In some embodiments, a first gas-liquid separator 102A is flowingly connected between the first outlet 68 of the cell 14 and the inlet 70 of the extractor 14. In some embodiments, a second gas-liquid separator 102B is flowingly connected between the outlet 98 of the carbon capture and storage unit 16 and the second inlet 96 of the cell 14. However, any suitable number of gas-liquid separators 102 between the cell 14 and the extractor 12 and / or carbon capture and storage unit 16 may be provided.Overview of methods of continuous production of metal carbonates and / or silica using an electrochemical cell for carbon capture and storage

[0303] FIG. 7C is a flow chart illustrating the basic steps of a method 3500 of continuous conversion of metal ion-containing solids according to one example embodiment of the invention.

[0304] In block 3502, an electrical current and / or potential is applied between an anode and a cathode.

[0305] In block 3503, a flow of a reduction reactant is supplied to the cathode chamber.

[0306] The reduction reactant undergoes a reduction reaction at the cathode to produce hydroxide ions (block 3506).

[0307] In block 3508, a flow of a oxidation reactant is supplied to the anode chamber.

[0308] In block 3510, hydrogen ions are produced in the cell. In some embodiments,the hydrogen ions are produced by electrolytic dissociation of water at the bipolar membrane. In some embodiments, the hydrogen ions are produced at the anode in the oxidation reaction.

[0309] In block 3512, a flow of electrolyte is caused to flow out of the cell to enter an extractor. The electrolyte may be electrolyte that has been acidified by the hydrogen ions formed in the cell.

[0310] In block 3514, the acidified electrolyte extracts the metal ion-containing solids in the extractor to yield a metal ion-enriched electrolyte. The metal ion-enriched electrolyte comprises the metal ions. In some embodiments, the extraction of the metal ion-containing solids by the acidified electrolyte additionally produces silica.

[0311] In block 3516, the metal ion-enriched electrolyte is supplied to the cell. In some embodiments, the metal ion-enriched electrolyte is supplied to the anode chamber. In some embodiments, the metal ion-enriched electrolyte is supplied to the chemical chamber.

[0312] In some embodiments of the invention, the metal ions permeate through a separator to the cathode chamber (block 3518). In some embodiments, the metal ions permeate through a separator from the anode chamber to the cathode chamber. In some embodiments, the metal ions permeate through a separator from the chemical chamber to the cathode chamber.

[0313] In some embodiments, a mixture comprising the metal ions and hydroxide ions are caused to flow out of the cathode chamber to enter a carbon capture and storage unit (block 3520).

[0314] In block 3524, a flow of carbon dioxide feedstock is supplied into the carbon capture and storage unit. The metal ions, the hydroxide ions and the feedstock comprising carbon dioxide may react to produce metal carbonate (block 3525).

[0315] The metal carbonate may be separated from one or more components contained in the mixture (block 3526). In some embodiments, the one or more components comprise an electrolyte. The electrolyte may be returned to the cell for re-use in subsequent reactions (block 3528).Example methodsContinuous production of metal carbonates and / or silica using a two-chamber electrochemical cell

[0316] In some example embodiments, a two-chamber electrochemical cell such as a cell illustrated in FIG. 7A is used in the continuous conversion of metal ion-containing solids. In such example embodiments, water may be used as the oxidation and reduction reactants in the oxidation and reduction reactions, respectively. The water molecules may be contained in the respective anolyte and catholyte solutions.

[0317] The water molecule may participate in a reduction reaction at the cathode to produce hydroxide ions. The water molecule may participate in an oxidation reaction at the anode to produce hydrogen ions.

[0318] A flow of electrolyte may be caused to flow out of the anode chamber to enter the extractor. The flow of electrolyte may be anolyte that has been acidified by the hydrogen ions formed in the oxidation reaction. The acidified electrolyte extracts the metal ion-containing solids to yield a metal-ion-enriched electrolyte. The extraction of the metal ion-containing solids by the acidified electrolyte may additionally produce silica. The metal-ion-enriched electrolyte may be supplied to the anode chamber within which the metal ions contained in the metal-ion-enriched electrolyte pass through a separator into the cathode chamber.

[0319] The metal ions and hydroxide ions may be caused to flow out of the cathode chamber to enter the carbon capture and storage unit within which the metal ions and hydroxide ions react with a carbon dioxide feedstock to form metal carbonates. The metal carbonates are separated from the electrolyte. The separated electrolyte may be supplied to the cathode chamber for re-use in subsequent reactions.Continuous production of metal carbonates and / or silica using a three-chamber electrochemical cell

[0320] In some example embodiments, a three-chamber electrochemical cell such as a cell illustrated in FIG. 7B is used in the continuous conversion of metal ioncontaining solids.

[0321] In some embodiments, a hydrogen-containing reactant such as water is supplied at the cathode. The hydrogen-containing reactant undergoes a reduction reaction at the cathode to produce hydroxide ions.

[0322] In some embodiments, the anolyte comprises the oxidation reactant. The oxidation reactant may comprise a base which contains hydroxide ions. The hydroxide ions participate in an oxidation reaction to produce water and oxygen gas.

[0323] Water molecules permeate into a bipolar membrane within which the water molecules are electrochemically dissociated into hydrogen ions and hydroxide ions. The hydrogen ions permeate through a cation exchange layer of the bipolar membrane to enter a chemical chamber. The hydrogen ions acidify the electrolyte circulated in the chemical chamber.

[0324] The acidified electrolyte may be caused to flow out of the chemical reaction chamber to the extractor within which the acidified electrolyte extracts the metal ioncontaining solids to yield the metal ion-enriched electrolyte. The metal ion-enriched electrolyte may be supplied to the chemical chamber within which the metal ions pass through a separator into the cathode chamber. The metal ions and hydroxide ions may then be caused to flow out of the cathode chamber to enter the carbon capture and storage unit within which the metal ions and hydroxide ions react with a carbon dioxide feedstock to form metal carbonates. The metal carbonates are separated from the electrolyte. The separated electrolyte may be supplied to the cathode chamber or chemical chamber for re-use in subsequent reactions.

[0325] The method 3500 may be tuned to optimize one or more of current efficiency, applied electrical potential to achieve a desired current efficiency, product selectivity, efficiency and reaction rate of each of the reactions by adjusting one or more of:• conditions of the flow cell such as temperature, pH, pressure, etc.; and / or• characteristics of the separator and bipolar membrane (if present) such as the thickness, porosity, composition, etc.; and / or• characteristics of the anode and / or cathode electrodes such as the material and method of fabrication; and / or• nature of the cathode and / or anode catalyst;• additional catalysts present; and / or• the type of anolyte, chemolyte and / or catholyte; and / or• flow rate and / or composition and / or concentration of the oxidation reactants (e.g., water), reduction reactant (e.g., water) and / or chemolyte and / or catholyte and / or anolyte; and / or• rate at which electrolyte is removed from the cell and / or returned to the cell; and / or• rate at which metal carbonates are removed from the cell; and / or• rate at which the acidified electrolyte is supplied to the extractor; and / or• rate at which the mixture comprising the metal and hydroxides and electrolyte are supplied to the carbon capture and storage unit; and / or• size of the filters used in the extractor and / or carbon capture and storage unit; and / or• size, surface area and composition of the metal-ion containing solids; and / or• presence of a chemical chamber and if present, distance across the chemical chamber between the bipolar membrane and the separator; etc.

[0326] In some embodiments, the electrolysis is operated at a temperature in the range of from 25 °C to about 60 °C. In some embodiments, the electrolysis is operated at a temperature less than about 60 °C.

[0327] In some embodiments, one or more of the anolyte 54, chemolyte 60, and / or catholyte 56 are heated to a selected temperature before being supplied to the anode chamber 18, chemical chamber 26, and cathode chamber 20 respectively. In some embodiments, one or more of the anolyte 54, catholyte 56 and / or chemolyte 60 are heated to a temperature in the range of from about 20 °C to about 60 °C.

[0328] In some example embodiments in which the bipolar membrane 28 separates the anode chamber 18 and the chemical chamber 26, the thickness of bipolar membrane 28 is in the range of from about 25 to about 250 pm. In some embodiments, the bipolar membrane 28 is a product commercially available under the product name Fumasep™ FBM. In some embodiments, the biopolar membrane 28 is fabricated by combining a cation exchange layer (such as a Nation™ 211 membrane) and an anion exchange layer (such as an Aemion™ CNN-8-25X membrane).

[0329] In some example embodiments, the separator 24 comprises an ion exchange membrane. The thickness of the ion exchange membrane may be in the range of from about 20 to about 200 pm. In some embodiments, the separator 24 is a Nation™ 117 membrane.

[0330] In some embodiments, a flow rate at which the anolyte 54, the chemolyte 60,and / or catholyte 56 are supplied to the respective anode chamber 18, chemical chamber 26 and cathode chamber 20 may for example be in the range of from about 30 to 800 mL min-1for an electrode having a geometric surface area of 5 cm2. The flow rate may be scaled according to the area of the electrode. In some embodiments, a flow rate at which the anolyte 54, the chemolyte, and / or the catholyte 56 are supplied to the respective anode chamber 18, chemical chamber 26 and cathode chamber 20 is in the range of from about 100 to 350 mL min-1for an electrode having a geometric surface area of 5 cm2.

[0331] In some embodiments, the concentration of the anolyte 54, the chemolyte 60 and / or the catholyte 56are supplied to the respective anode chamber 18, chemical chamber 26 and cathode chamber 20 is in the range of from about 0.1 to about 5 M, and in some embodiments, less than about 5 M.

[0332] In some embodiments, the pH of the electrolyte 64 (e.g., one or more of anolyte 54, the chemolyte 60 and / or the catholyte 56) supplied to the extractor 12 is less than about 3, and in some embodiments, in the range of from about 0.2 to 3.

[0333] In some embodiments, the pH of cathode chamber 20 is maintained in the range of from about 9 to about 14 during electrolysis. In some embodiments, the pH of cathode chamber 20 is maintained in the range of from about 10 to about 14 during electrolysis.

[0334] In some example embodiments in which carbon dioxide feedstock comprises air, the concentration of the carbon dioxide supplied to the cathode chamber is up to about 400 ppm, including any value or subrange greater than 0 and between 0 to 400 ppm.

[0335] In some example embodiments in which the carbon dioxide feedstock comprises flue gas, the concentration of the carbon dioxide supplied to the cathode chamber is between about 3 to 40 vol%, and in some embodiments, between 5-20 vol%, including any value or subrange therebetween.

[0336] In some example embodiments in which carbon dioxide feedstock comprises air, a flow rate at which the carbon dioxide feedstock is supplied to the cathode chamber 20 may for example be up to about 2000 seem including any value or subrange therebetween, for an electrode having a geometric surface area of 4 cm2. The flow rate may be scaled according to the area of the electrode.

[0337] In some example embodiments in which carbon dioxide feedstock comprises flue gas, a flow rate at which the carbon dioxide feedstock is supplied to the cathode chamber 20 may for example be in the range of from about 50 to 200 seem, including any value or subrange therebetween, for an electrode having a geometric surface area of 4 cm2. The flow rate may be scaled according to the area of the electrode.

[0338] In summary, one example aspect of the invention provides continuous systems and methods to convert metal-ion containing solids to metal carbonate, and in some embodiments, additionally produce silica. Applications of such continuous systems and methods involve carbon dioxide capture and storage. This conversion may involve the conversion of a silicate mineral (e.g., CaSiOs) to calcium carbonate (CaCOs). It will however be understood that the systems and methods described herein may be used to convert any suitable metal-ion containing solids to metal carbonates. One non-limiting example is in the conversion of magnesium-ion containing solids to (MgCOs).

[0339] The invention is further described with reference to the following specific examples, which are not meant to limit the invention, but rather to further illustrate it.ExamplesExample 1 - Systems and methods for converting metal-ion containing solids for carbon dioxide capture and storage using a two-chamber cell

[0340] An electrochemical cell of the type illustrated in FIG. 1 and the method of performing electrolysis illustrated in FIG. 2 were used to convert CaSiOs as the metalion containing solids 74 into calcium carbonate 90 and silica 75 where the metal ion is calcium ion. The system may be referred to as a “water electrolyzer”.

[0341] In this example, the water electrolyzer comprises a cathode 22 that is made of a nickel foam and an anode 19 that is made of a lrO2 catalyst deposited on carbon paper. The separator 24 which separates the anode 19 from the cathode 22 is a Nation™ 117 CEM. The cathode 22 and anode 19 each has a 4 cm2active area, are pressed between anodic and cathodic serpentine flow plates. The flow plates were made of titanium. The catholyte 56 comprises 0.5 M KCI. CO2 gas was bubbled constantly in the catholyte 56 during electrolysis. The pH within the cathode chamber 20 was maintained at 11 during electrolysis. The anolyte 54 comprises 0.5M KNO3solution containing 20 g / L CaSiOs. The flow rate of the anode and cathode feedstock was 100 mL min-1. Water was reduced in the cathode chamber 20 and oxidized in the anode chamber 18. A schematic of the water electrolyzer used in these examples is shown in FIG. 8A.Benchmarking of silicate dissociation.

[0342] The inventors validated silicate mineral dissolution in the water electrolyzer. The inventors first tracked the pH of the anolyte both in the presence and absence of CaSiOs. As shown in FIG. 8B, without CaSiOs in the anolyte, the pH decreased from 7 to 1 .6 over the course of 60 minutes of electrolysis at 100 mA cm-2, confirming the production of acid from OER. When electrolysis was repeated with 20 g L-1CaSiOs in the anolyte, the pH decreased from 10.2 to 6.8. The higher final pH indicated that H+ions were being consumed by the reaction with CaSiOs.Validating CO2 capture and mineralization

[0343] The water electrolyzer was then used to demonstrate a proof-of-concept for integrated CO2 capture and mineralization. The cathode reservoir served as the precipitation reactor, containing a 0.5 M KCI solution. Concurrently, the anode was supplied with a 0.5 M solution of KNO3 with 20 g L-1CaSiOs, which was stirred constantly during electrolysis. The cathode and anode chambers were separated by a Nation 117 CEM.

[0344] The anolyte was recirculated during electrolysis, to accumulate Ca2+ions released from the CaSiOs by the acid from OER. The Ca2+ions would then migrate through the CEM. The catholyte of the water electrolyzer was bubbled with CO2 gas during electrolysis in order to capture CO2 and generate carbonates, which in turn would react with the Ca2+in solution to form CaCOs. The operating pH was maintained at about 11 during electrolysis at 100 mA cm-2. The inventors believed this pH to be ideal because it is sufficiently alkaline to form carbonate ions from the reaction of OH- and CO2, while preventing the precipitation of Ca(OH)2, which is occurs more readily at pH>12. The catholyte was continuously stirred using a magnetic stir bar during operation and recirculated in order to accumulate the precipitate for subsequent characterization.

[0265] The catholyte that was initially clear turned cloudy during the 1 h of electrolysis at 100 mA cm-2, indicating the formation of precipitate. This precipitate was isolated and dried overnight in an oven at 60 °C. The isolated solid was shown by powder XRD to contain two polymorphs of CaCOs, calcite and aragonite (FIG. 9A). A total of 0.15 g of CaCOs was produced, corresponding to 0.07 g of CO2 stored. This value can be increased by modifying the OEM to be selective for divalent cations and by employing a calcium-containing electrolyte.

[0345] The voltage of the water electrolyzer remained steady at approximately 3.0 V electrolysis at 100 mA cm-2(FIG. 9B). This value represents the lowest voltage achieved by a water electrolyzer used to facilitate CO2 mineralization.

[0346] In summary, the design objective of the water electrolyzer was to integrate all of the steps necessary for carbon capture and storage into a single two-chamber reactor. This objective was met by demonstrating electrolytic silicate dissolution and carbonate formation from CO2 in a single unit. This electrolytic weathering was made possible by acid generated by OER to decompose silicate rock, a CEM that enabled Ca2+migration into the cathode for mineralization of CO2. This work represents the first instance of electrodialytic mineralization of CO2 in a two-chamber water electrolyzer, enabling scalable CO2 storage.Example 2 - Systems and methods for converting metal-ion containing solids for carbon dioxide capture and storage which integrate the oxidation of sulfur- containing species

[0347] An electrochemical cell of the type illustrated in FIG. 2A and the method of performing electrolysis illustrated in FIG. 3 were used to convert MgSiOs as the metalion containing solids 74 into magnesium carbonate 90, and additionally producing silica (SiO2) by integrating a SOs2' oxidation reaction (SO3OR) at the anode 19 while HER occurs at the cathode 22. The system may be referred to as a “sulfite electrolyzer”.

[0348] In this example, the sulfite electrolyzer comprises a cathode 22 that is made of a nickel foam and an anode 19 that is made of a platinum / carbon (Pt / C) catalyst deposited on carbon paper. The anode 19 was prepared by dispersing 8 mg of 1 :1 Pt / HSA Ketjenblack nanoparticles into an ethanol solution containing 10 pL of 20 wt%Nafion ionomer solution. The resulting dispersion was deposited onto carbon paper with a commercial gravity-fed pneumatic spray-coater, with a catalyst loading density of 2 mg cm-2. The cathode 22 and anode 19 each has an active area of 4 cm2, and are pressed between anodic and cathodic serpentine flow plates. The flow plates were made of titanium. The anolyte 54 comprises 0.1 M Na2SOs solution. The catholyte 56 comprises 1 .0 M NaCI. The flow rate of the anolyte 54 and catholyte 56 was 100 mL min-1. A separator 24 which separates the anode 19 from the cathode 22 is a polyaniline-coated CEM. In these examples, SC>32'was used as the sulfur- containing species with a lower oxidation state 47. The SOs2' was oxidized in the anode chamber 18 to produce H+and SC>42'. SC>42' is the sulfur-containing species with a higher oxidation state 51. Water was reduced in the cathode chamber 20 to generate OH'. A schematic of the sulfite electrolyzer used in these examples is shown in FIG. 10.Benchmarking of electrolyzer voltages

[0349] The inventors benchmarked the cell voltage (Eceii) of the sulfite electrolyzer against a sulfate salt-splitting water electrolyzer at an applied current density of 100 mA cm-2for 60 minutes of electrolysis. The configuration of this “salt-splitting water electrolyzer” was identical to the sulfite electrolyzer, except that 0.1 M SO42-was fed to the anode chamber instead of the 0.1 M SOs2-.

[0350] The Eceii of the sulfite electrolyzer remained constant at 2.2 V during electrolysis (FIG. 11 A). The small voltage rise is due to a change in electrolyte concentration, not electrolyzer degradation. The absence of gaseous products exiting the anode chamber of the electrolyzer was consistent with SO3OR occurring instead of OER. Conversely, the water electrolyzer operated at 4.2 V at the same applied current density over 60 minutes of electrolysis (FIG. 11 A), and gas evolution was observed at the anode, consistent with O2(g) formation. The 2 V increase for the saltsplitting water electrolyzer far exceeded the difference between the half-cell potentials of OER and SO3OR. The inventors therefore hypothesized that the Pt / C anode possessed poor OER activity, leading to a high overpotential. The strong binding energy of oxygen-containing intermediates to Pt during electrolysis is known to reduce the available surface area for OER. The inventors then performed electrolysisin the salt-splitting water electrolyzer using an lrO2 / C anode instead of Pt / C, because anodes based on I rC>2 are known to exhibit higher OER activity and corrosion resistance. An Eceii of 3.3 V during electrolysis was measured (FIG. 11 A). This voltage is significantly lower than the OER experiment with Pt / C, but still >1 V higher than the sulfite electrolyzer. These results are consistent with SOs2-being easier to oxidize at the anode than water. Polarization curves further illustrate this point, with the sulfite electrolyzer demonstrating lower Eceii values than the salt-splitting water electrolyzer across the range of applied current densities (25-1000 mA cm-2, FIG. 11 B).Silicate dissociation in the sulfite electrolyzer.

[0351] Using the more energy-efficient sulfite electrolyzer in hand, the inventors performed operando silicate mineral dissociation using the acid produced from SO3OR. For this experimental campaign, the electrolysis experiments were repeated for 60 minutes at 100 mA cm-2, but with an anolyte solution containing milled Mg2SiO4 at concentrations of up to 30 g L-1in 0.1 M SOs2-. The anolyte was stirred continuously during electrolysis. All other experimental conditions were held constant with previously described conditions.

[0352] When the slurry contained 30 g L-1Mg2SiO4, the cell voltage increased from 2.6 V to 14 V after just 45 minutes of electrolysis at 100 mA cm-2. After disassembling the cell, white deposits were observeds on the cathode-facing side of the CEM. The CEM also became dehydrated and the previously smooth texture was now wrinkled and cracked. Moreover, precipitate formation was observed in the catholyte. This solid was determined by powder X-ray diffraction (XRD) techniques to be predominantly brucite (Mg(OH)2). These findings confirmed that Mg2+was indeed being released from Mg2SiO4, however, it was crossing the membrane and reacting with OH- produced at the cathode to form Mg(OH)2 deposits. This issue was likely compounded by the high local pH in the interfacial region between the membrane and cathode.

[0353] This hypothesis was validated by repeating these experiments with dissolved Mg2+in the anolyte (prepared by adding 0.5 M MgSO4 prior to electrolysis) rather than Mg2SiO4. The Eceii increased from 2.8 V to 10 V after less than 40 minutes of electrolysis, similar to the increase observed when Mg2SiO4 was present in theanolyte. Furthermore, the same white Mg(OH)2 deposits were observed on the cathode-facing side of the CEM and cathode after the cell was disassembled. These findings further support the notion that dissolved Mg2+crossover and subsequent precipitate formation are the cause of Eceii increasing during operando mineral dissolution.

[0354] Mg(OH)2 formation can be mitigated through modification of the CEM. For example, by depositing a polyaniline (PANI) coating on either side of the CEM. In the absence of Mg2SiO4, the sulfite electrolyzer containing the PANI-modified CEM maintained an Eceii of 2.2 V over 60 minutes of electrolysis at 100 mA cm-2. When a slurry containing 30 g L-1of Mg2SiO4 was fed to the anode chamber, the voltage only increased from 2.4 V to 2.7 V during the 60-minute experiment. No precipitate was observed in the cathode chamber following electrolysis, and cell disassembly revealed no deposits on the surface of the PANI-modified CEM.

[0355] The selective blocking of divalent cations such as Mg2+and Ca2+using PANI- modified CEMs can be attributed partly to the large hydrated radii of these ions, resulting in slower transport through the dense PANI layer. For example, the effective radii of Mg2+is 0.43 nm, whereas the effective radii of Na+is 0.36 nm. Moreover, the charged PANI layer results in a Donnan potential at the solution|membrane interface for divalent cations such as Mg2+due to their larger electrostatic repulsion. Finally, the transport of divalent cations such as Mg2+through the membrane is less energetically favorable than Na+due to a higher dehydration energy (AGdehydrate of Mg2+= 1830 kJ mol-1and AGdehydrate of Na+= 430 kJ mol-1).

[0356] Silicate mineral dissolution in the sulfite electrolyzer was validated using the PANI-modified CEM. The pH of the anolyte both in the presence and absence of Mg2SiO4 was tracked. Without Mg2SiO4 in the anolyte, the pH decreased from 8.8 to 1 .8 over the course of 60 minutes of electrolysis at 100 mA cm-2, confirming the production of acid from SO3OR. A buffering effect was initially observed in the anolyte, as H+from SO3OR reacted with SO32-to form HSO3-. The buffer capacity was exceeded after approximately 25 minutes, at which point the pH decreased rapidly to 1.8. When electrolysis was repeated with 30 g L-1Mg2SiO4 in the anolyte, the pH decreased from 8.9 to 4.9. The higher final pH indicated that H+ions were being consumed by the reaction with Mg2SiO4.

[0277] Additional electrolysis experiments were performed. The solids present in the anolyte before and after electrolysis using powder XRD were characterized. The diffractograms of the solid prior to electrolysis are consistent with amorphous Mg2SiC>4. Following electrolysis, the cell was disassembled and the remaining white solids in the anolyte were isolated and dried in an oven at 60 °C overnight. The diffractogram exhibited a broad peak centered at 20 = 25° consistent with amorphous SiC>2, the only solid product from the dissociation of Mg2SiC>4. These findings indicate the dissolution of Mg2SiC>4 during electrolysis.CO2 capture and metal ion carbonation in the sulfite electrolyzer

[0357] The sulfite electrolyzer can be used for integrated CO2 capture and mineralization. In an experiment, the cathode reservoir served as the precipitation reactor, containing a 1.0 M NaCI solution seeded with 0.5 M MgSC>4 (Mg2+and SO42-are products of magnesium silicate mineral dissolution and SO3OR, respectively). Concurrently, the anode was supplied with a 1.0 M solution of Na2SOs. This solution was recirculated during electrolysis to accumulate H2SO4. The cathode and anode chambers were separated by a PANI-modified CEM.

[0358] The catholyte of the sulfite electrolyzer was bubbled with CO2 gas during electrolysis in order to capture CO2 and generate carbonates, which in turn would react with the Mg2+in solution to form MgCOs. An operating pH of 9.5-10 was maintained during electrolysis at 100 mA cm-2. The inventors determined this pH to be ideal because it is sufficiently alkaline to form carbonate ions from the reaction of OH- and CO2, while preventing the precipitation of Mg(OH)2, which occurs more readily at pH>10. The catholyte was continuously stirred using a magnetic stir bar during operation and recirculated in order to accumulate the precipitate for subsequent characterization. Concurrently, the anolyte was recirculated to accumulate acid in the anode reservoir.

[0359] Over the course of electrolysis at a constant applied potential of 100 mA cm-2, the clear catholyte turned increasingly cloudy as precipitate formed. After the experiment, precipitate was collected by vacuum filtration and dried in an oven overnight at 60 °C. The resulting powder was characterized using XRD and was determined to be exclusively the magnesium carbonate mineral nesquehonite(MgCO3'3H2O, FIG. 12A). Approximately 0.42 g of MgCOs SHhO was produced in 60 minutes, corresponding to a carbon storage rate (i.e., the rate at which CO2 is converted into a carbonate mineral) of 5.1 x10-5mol min-1.

[0360] In summary, the integrated electrolyzer demonstrated a stable cell voltage during electrolysis for 60 minutes at a constant applied current density of 100 mA cm-2. The initial Eceii was 2.1 V, increasing to 2.3 V at the end of the 60-minute experiment. These values are similar to the 2.2 V observed during electrolysis in sulfite electrolyzer when uncoupled from silicate dissociation or CO2 capture and mineralization.

[0361] The rate of SO3OR-driven carbonate mineral formation rate was dependent on current density. Mineralization experiments were repeated with the sulfite electrolyzer at current densities up to 400 mA cm-2(FIG. 12B). The catholyte pH was maintained between 9.5-10 throughout electrolysis. The rate of carbonate mineral formation increased from an average of 4.6 (±1.1) xio-5mol min-1at 100 mA cm-2to 1.4 (±0.28) xio-4mol min-1at 400 mA cm-2. The inventors posit that higher current densities correspond to increased carbonate formation. As the reaction rate increases, more OH- is generated from HER, which can in turn react with more CO2 to generate carbonates for subsequent mineral formation.Energy analysis for economical CO2 capture and storage

[0362] The energy intensities of the sulfite electrolyzer during these experiments ranged from 5.4 - 23.8 MWh ton-1of CO2. Importantly, these experiments demonstrate sulfite electrolysis at current densities greater than 100 mA cm2. The described system and method can use waste sulfur feedstock to electrolytically drive CO2 capture and sequestration at scale.Example 3 - Systems and methods for converting metal-ion containing solids for carbon dioxide capture and storage using a three-chamber cell

[0363] An electrochemical cell of the type illustrated in FIG. 5 and the method of performing electrolysis illustrated in FIG. 6 were used to convert CaSiOs as the metalion containing solids 74 into calcium carbonate 90, and additionally producing silica 75 where the metal ion is calcium ion. The system may be referred to as a“weathering electrolyzer”.

[0364] In this example, the weathering electrolyzer comprises three chambers where a chemical chamber 26 is arranged between an anode chamber 18 and a cathode chamber 20. A bipolar membrane separates the anode and cathode chambers 18, 20. A separator 24 which comprises a Ca2+-selective cation exchange membrane separates the chemical chamber 26 and the cathode chamber 20.

[0365] A cathode 22 is exposed to the cathode chamber 20. The cathode is made of a nickel foam. An anode 19 is exposed to the anode chamber 18. The anode 19 is made of a nickel foam. The anolyte 54 comprises 1.0 M KOH solution. The catholyte 56 comprises 1.0 M KOI solution. The chemical chamber 26 is supplied with a flow of a slurry of 10 g L'1CaSiOs in 1 .0 M CaC solution. Under reverse bias, the BPM 28 supplied OH' to the anode 19 to be oxidized into O2 and H2O. The BPM also supplied H+to the chemical chamber 26 to facilitate dissolution of CaSiOs. In the cathode chamber 20, H2O was reduced to produce H2 gas and OH'. The formation of CaCOs was enabled by the transport of Ca2+ions from the chemical chamber 26 through a Ca2+-selective OEM 26 for reaction with an external supply of CO2 in the cathode chamber 20. A schematic of the weathering electrolyzer used in these examples is shown in FIG. 13.Sustained acid generation for accelerated silicate dissolution

[0366] To validate acid generation in the chemical chamber, the pH of the chemical chamber electrolyte (“chemolyte”) during electrolysis without CaSiOs present was measured. The pH decreased from 6.6 to 1.1 after 1 hour of electrolysis (FIG. 14A), thereby confirming that strong acid was being generated in the chemical chamber. When the CaSiOs slurry was added to the chemical compartment (prior to electrolysis), the chemolyte pH immediately increased from 6.6 to 9.6. After 1 hour of electrolysis, the pH dropped from 9.6 to 6.9 (FIG. 14A). The higher pH signaled that the acid being generated in the chemical chamber was consumed by the reaction with CaSiOs.

[0367] The dissolution of CaSiOs in the chemical chamber during electrolysis was quantified by measuring the total calcium concentration in solution [Ca2+(aq)], in both the chemical and cathode chambers, using inductively coupled plasma opticalemission spectroscopy (ICP-OES). The solid CaSiOs is introduced to the reactor as a slurry in 1.0 M CaC solution. Within the chemical chamber, the initial [Ca2+(aq)] was measured to be 995 mmol L"1, matching the 1.0 M CaC composition of the chemolyte. The [Ca2+(aq)] increased over the first 20 minutes of electrolysis to 1020 mmol L"1, where it remained constant over the remainder of the 1-hour electrolysis run. Meanwhile, the [Ca2+(aq)] of the catholyte increased linearly from 0.2 to 15 mmol L“1over the 1 hour of electrolysis FIG. 14B).

[0368] These experiments were repeated, the solids present in the chemical chamber before and after electrolysis were characterized using powder X-ray diffraction (XRD). Diffractograms recorded on the solid before electrolysis show a mixture of CaSiOs, SiC>2 and the impurity rankinite (Ca3Si2O?). After electrolysis, the cell was disassembled and the remaining white solids in the chemical chamber were isolated and dried in an oven at 60 °C overnight. The diffractograms detected trace amounts of CaSiOs, with a broad peak centered at 20 = 25° consistent with short range ordered SiC>2. Furthermore, the atomic Ca:Si ratio, determined by energy-dispersive X-ray (EDX) spectroscopy, of the solid that was added to the chemical chamber was reduced from 1.37:1 to 0.12:1 after 1 hour of electrolysis. This trend is consistent with the dissolution of CaSiOs.CO2 capture and mineralization in the cathode chamber

[0369] To demonstrate OH- production and, in turn, direct CO2 capture and mineralization in the cathode chamber, the catholyte pH during electrolysis at 100 mA cm-2was continuously monitored. In control experiments conducted without CaSiOs added to the chemical chamber and without an external supply of CO2 to the cathode, the pH of the catholyte increased from 6.9 to 12.7 after 1 hour of electrolysis (FIG. 15A, Experiment A). This experiment confirmed the generation of OH- at the cathode. For the same experiment with CaSiOs added to the chemical chamber, the pH increased from 6.4 to 12.8 after 1 hour of electrolysis, again confirming the production of OH- (FIG. 15A, Experiment B). No solids were formed in the cathode chamber over the course of this control experiment.

[0370] CO2 was introduced into the cathode chamber, and CaSiOs into the chemical chamber. A simulated flue gas (10% CO2, 90% N2) was first used as the feedstock tothe cathode chamber at a flow rate of 0.2 L min-1. Over the course of 1 hour of electrolysis, the formation of a white solid in the cathode chamber was observed. The isolated solid was shown by powder XRD to contain various forms of CaCOs, including calcite, aragonite, and vaterite (FIG. 15B). The catholyte pH increased from 7.0 to 11.7 over the course of the electrolysis experiment (FIG. 15A, Experiment C). The lower pH of the catholyte with CO2 (pH 11 .7 c.f. pH 12.7 without CO2) is consistent with a larger fraction of the electrolytically generated OH- being consumed through reaction with CO2 and Ca2+to form solid CaCOs.

[0371] This experiment demonstrates accelerated rock weathering in an electrochemical reactor. From the 2.5 g of CaSiOs added to the chemical chamber, 0.87 g of CaSiOswas dissolved during 1 hour of electrolysis to form 0.50 g of CaCOs and stored 0.22 g of CO2. Natural weathering would take 6000 hours to store that amount of CO2 from the same amount of CaSiOs. This difference amounts to an increase over natural rock weathering by three orders of magnitude (FIG. 16).

[0372] In addition to measuring the CaCOs produced in the cathode chamber, other electrolyzer performance metrics during electrolysis were tracked, including the full cell voltage (Vceii) and acid production within the chemical chamber. In experiments conducted without CO2, the Vceii stabilized after 10 minutes of electrolysis at a value of approximately 4.0 V. The Vceii increased slightly as electrolysis continued, but remained below 4.4 V over the 1 hour campaign. The same Vceii profiles were observed in experiments where simulated flue gas was supplied to the cathode. Moreover, the supply of CO2 did not cause notable variations in acid production compared to the control experiments, as the pH decreased from 9.5 to 6.7 for all experiments. This finding indicates nearly all acid generated in the chemical chamber reacts with CaSiOs, and that all of the corresponding Ca2+migrates to the cathode chamber.

[0373] The inventors sought to demonstrate mineralization using CO2 sourced from air (i.e. , 0.04% of CO2), following the same experimental procedures. Over the course of 1 hour of electrolysis, the catholyte pH again increased from 5.9 to 12.9 (FIG. 15A, Experiment D), and the chemolyte pH decreased from 9.3 to 6.8. The Vceii profiles were also effectively the same. The turbidity of the catholyte increased following electrolysis, indicating the formation of the CaCOs precipitate. The CaCOs solid wasisolated, dried, and weighed to be 15.6 mg. This amount was far less than the 0.50 g of CaCOs made from the same 2.5 g of CaSiOs starting material (and the same 0.87 g of dissolved CaSiOs) when using a flue gas. The diffractograms showed that the white solid formed when sourcing CO2 from air contained trace amounts of Ca(OH)2 peaks (Fig. 15B). This Ca(OH)2was not detected when using flue gas. The inventors attrivute this difference to the higher pH of the catholyte when air is supplied to the cathode compared to simulated flue gas.

[0374] The fraction of CO2 fed to the cathode chamber that was converted into CaCOs using the metric, “sequestration efficiency” was quantified. The sequestration efficiency is defined herein as the ratio of the number of moles of CaCOs that precipitated in the cathode chamber after electrolysis (ncacos), to the total number of moles of CO2 purged into the cathode chamber during electrolysis (r?co2), times 100%. These values were calculated to be 9% and 10% for experiments conducted with simulated flue gas and air, respectively (FIG. 16B). The inventors hypothesized these low values to be due to deficiencies of carbonate ions in the cathode chambers for both experiments. To test for this, the inventors calculated the fraction of Ca2+dissolved from silicate in the chemical chamber that was carbonated in the catholyte. This “carbonation efficiency”, defined as the ratio of ncacos to the number of moles of Ca2+dissolved from CaSiOs (nca2+, chemoiyte) times 100%, was determined to be 3.1 % and 67% when CO2 was sourced from air and flue gas, respectively (FIG. 16C). The low value for air is consistent with insufficient carbonates available to react with Ca2+. Moreover, the higher catholyte pH observed when using air was consistent with less OH- being consumed, and thus fewer carbonates being formed.

[0375] When using flue gas, the majority of Ca2+is carbonated, yet the sequestration efficiency is still low. The inventors hypothesized that the poor uptake of gaseous CO2 by the catholyte was a major factor for the low sequestration efficiency. An airstone was connected to the gas purging tube to decrease bubble size and, in turn, increase the gas-liquid interface, to increase the amount of CO2 captured by the catholyte. When air was fed to the cathode, the airstone increased the rate of CO2 conversion from 10% to 26%.

[0376] In summary, the design objective of the weathering electrolyzer was to integrate all of the steps necessary for carbon capture and storage into a single step.This objective was met by demonstrating electrolytic silicate dissolution and carbonate formation using CO2 sourced from simulated flue gas and air, all in a single electrochemical reactor. This electrolytic weathering was made possible by a BPM that provided acid to a chemical chamber to decompose silicates, and by a CEM that enabled Ca2+migration into a cathode chamber for mineralization with CO2. The weathering electrolyzer is capable of storing concentrated CO2 sources such as flue gas, or dilute CO2 sources such as air. This work presents an entirely new approach to the permanent removal and storage of CO2.Addition of amino acid and / or amino acid salts to catholyte

[0377] The results shown in FIGS. 17-19 demonstrate that the addition of amino acid and / or amino acid salt in the catholyte promotes efficient carbon dioxide capture and mineralization to carbonate solids in the electrolysis using the weathering electrolyzer.

[0378] FIG. 17 are plots illustrating CO2 mineralization efficiencies (top) and carbonation efficiencies (bottom) of 1 hour electrolysis for the weathering electrolyzer with air purging into catholyte with varied amino acid (salt) at flow rate of 2000 seem. Glycine (Gly) and potassium glycinate (Gly-K) are used as amino acid and amino acid salt. Total amino acid (salt) concentration varied from 0.1 to 1 M.

[0379] FIG. 18 are plots illustrating cell voltage profile of the weathering electrolyzer over 1 hour electrolysis with air purging at flow rate of 2000 seem into catholyte with amino acid (salt) at concentration of 1 M (top) and 0.1 M (bottom). Glycine (Gly) and potassium glycinate (Gly-K) are used as amino acid and amino acid salt.

[0380] FIG. 19 are XRD profiles of calcium carbonate obtained at cathode chamber of the weathering electrolyzer over 1 hour electrolysis with air purging at flow rate of 2000 seem into catholyte with amino acid (salt) at concentration of 0.1 M. Glycine (Gly) and potassium glycinate (Gly-K) are used as amino acid and amino acid salt.Interpretation of Terms

[0381] Unless the context clearly requires otherwise, throughout the description and the claims:• “comprise”, “comprising”, and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in thesense of “including, but not limited to”;• “connected”, “coupled”, or any variant thereof, means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof;• “herein”, “above”, “below”, and words of similar import, when used to describe this specification, shall refer to this specification as a whole, and not to any particular portions of this specification;• “or”, in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list;• the singular forms “a”, “an”, and “the” also include the meaning of any appropriate plural forms. These terms (“a”, “an”, and “the”) mean one or more unless stated otherwise;• “and / or” is used to indicate one or both stated cases may occur, for example A and / or B includes both (A and B) and (A or B);• “approximately” when applied to a numerical value means the numerical value ± 10%;• where a feature is described as being “optional” or “optionally” present or described as being present “in some embodiments” it is intended that the present disclosure encompasses embodiments where that feature is present and other embodiments where that feature is not necessarily present and other embodiments where that feature is excluded. Further, where any combination of features is described in this application this statement is intended to serve as antecedent basis for the use of exclusive terminology such as "solely," "only" and the like in relation to the combination of features as well as the use of "negative" limitation(s)” to exclude the presence of other features; and• “first” and “second” are used for descriptive purposes and cannot be understood as indicating or implying relative importance or indicating the number of indicated technical features.

[0382] Words that indicate directions such as “vertical”, “transverse”, “horizontal”,“upward”, “downward”, “forward”, “backward”, “inward”, “outward”, “left”, “right”, “front”, “back”, “top”, “bottom”, “below”, “above”, “under”, and the like, used in this description and any accompanying claims (where present), depend on the specific orientation of the apparatus described and illustrated. The subject matter described herein may assume various alternative orientations. Accordingly, these directional terms are not strictly defined and should not be interpreted narrowly.

[0383] Where a range for a value is stated, the stated range includes all sub-ranges of the range. It is intended that the statement of a range supports the value being at an endpoint of the range as well as at any intervening value to the tenth of the unit of the lower limit of the range, as well as any subrange or sets of sub ranges of the range unless the context clearly dictates otherwise or any portion(s) of the stated range is specifically excluded. Where the stated range includes one or both endpoints of the range, ranges excluding either or both of those included endpoints are also included in the invention.

[0384] Certain numerical values described herein are preceded by "about". In this context, "about" provides literal support for the exact numerical value that it precedes, the exact numerical value ±5%, as well as all other numerical values that are near to or approximately equal to that numerical value. Unless otherwise indicated a particular numerical value is included in “about” a specifically recited numerical value where the particular numerical value provides the substantial equivalent of the specifically recited numerical value in the context in which the specifically recited numerical value is presented. For example, a statement that something has the numerical value of “about 10” is to be interpreted as: the set of statements:• in some embodiments the numerical value is 10;• in some embodiments the numerical value is in the range of 9.5 to 10.5; and if from the context the person of ordinary skill in the art would understand that values within a certain range are substantially equivalent to 10 because the values with the range would be understood to provide substantially the same result as the value 10 then “about 10” also includes:• in some embodiments the numerical value is in the range of C to D where C and D are respectively lower and upper endpoints of the range that encompasses all of those values that provide a substantial equivalent to thevalue 10.

[0385] Specific examples of systems, methods and apparatus have been described herein for purposes of illustration. These are only examples. The technology provided herein can be applied to systems other than the example systems described above. Many alterations, modifications, additions, omissions, and permutations are possible within the practice of this invention. This invention includes variations on described embodiments that would be apparent to the skilled addressee, including variations obtained by: replacing features, elements and / or acts with equivalent features, elements and / or acts; mixing and matching of features, elements and / or acts from different embodiments; combining features, elements and / or acts from embodiments as described herein with features, elements and / or acts of other technology; and / or omitting combining features, elements and / or acts from described embodiments.

[0386] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any other described embodiment(s) without departing from the scope of the present invention.

[0387] Any aspects described above in reference to apparatus may also apply to methods and vice versa.

[0388] Any recited method can be carried out in the order of events recited or in any other order which is logically possible. For example, while processes or blocks are presented in a given order, alternative examples may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and / or modified to provide alternative or subcombinations. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, simultaneously or at different times.

[0389] Various features are described herein as being present in “some embodiments”. Such features are not mandatory and may not be present in all embodiments. Embodiments of the invention may include zero, any one or any combination of two or more of such features. All possible combinations of suchfeatures are contemplated by this disclosure even where such features are shown in different drawings and / or described in different sections or paragraphs. This is limited only to the extent that certain ones of such features are incompatible with other ones of such features in the sense that it would be impossible for a person of ordinary skill in the art to construct a practical embodiment that combines such incompatible features. Consequently, the description that “some embodiments” possess feature A and “some embodiments” possess feature B should be interpreted as an express indication that the inventors also contemplate embodiments which combine features A and B (unless the description states otherwise or features A and B are fundamentally incompatible). This is the case even if features A and B are illustrated in different drawings and / or mentioned in different paragraphs, sections or sentences.

[0311] It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, omissions, and sub-combinations as may reasonably be inferred. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

Claims

CLAIMS1 . A method of converting metal-ion containing solids comprising: applying an electrical potential between an anode and a cathode of an electrochemical cell, wherein the electrochemical cell comprises an anode chamber, a cathode chamber, and a separator separating the anode chamber and the cathode chamber; oxidizing a first hydrogen-containing reactant, at the anode, to form hydrogen ions; reducing a second hydrogen-containing reactant, at the cathode, to form hydroxide ions; supplying a feedstock comprising a metal-ion containing solid to the anode chamber; reacting, at the anode chamber, the metal-ion containing solid with the hydrogen ions formed at the anode to yield metal ions and / or silica; permeating through the separator the metal ions from the anode chamber to the cathode chamber; supplying a carbon dioxide feedstock to the cathode chamber; and reacting, in the cathode chamber, the hydroxide ions formed at the cathode with the carbon dioxide feedstock and the metal ions to yield metal carbonate.

2. The method according to claim 1 , wherein the first hydrogen-containing reactant comprises water.

3. The method according to claim 1 or 2, wherein the second hydrogencontaining reactant comprises water.

4. The method according to any one of claims 1 to 3, further comprising supplying a flow of an anolyte and / or a flow of an anolyte comprising the feedstock comprising the metal-ion containing solids to the anode chamber.

5. The method as defined in claim 4, wherein the cations of the anolyte comprise an alkali metal ion and / or alkaline earth metal ion.

6. The method as defined in the preceding claim, wherein the anolyte comprise one or more of NaCI, KCI, CaCh and MgSCU.

7. The method as defined in any one of claims 4 to 6, wherein a concentration of the anolyte is up to about 14 M.

8. The method as defined in any one of claims 4 to 7, wherein a concentration of the anolyte is in the range of from about 0.1 M to about 1.0 M.

9. The method as defined in any one of claims 1 to 8, further comprising supplying a flow of a catholyte into the cathode chamber.

10. The method as defined in claim 9, wherein the cations and / or anions of the catholyte are divalent and / or monovalent.11 . The method as defined in claim 9 or 10, wherein the cations of the catholyte comprise an alkali metal ion and / or alkaline earth metal ion.

12. The method as defined in any one of claims 9 to 11 , wherein a concentration of the catholyte is up to about 14 M.

13. The method as defined in any one of claims 9 to 12, wherein a concentration of the catholyte is in the range of from about 0.1 M to about 1.0 M.

14. The method as defined in any one of claims 1 to 13, wherein the carbon dioxide feedstock comprises a gas and / or an aqueous solution.

15. The method as defined in any one of claims 1 to 14, wherein the carbon dioxide feedstock comprises a capture solution comprising bicarbonate and / or carbonate ions.

16. The method as defined in any one of claims 1 to 15, wherein the carbon dioxide feedstock comprises air, flue gas and / or pure carbon dioxide gas.

17. The method as defined in any one of claims 1 to 16, wherein the separator comprises an ion exchange membrane.

18. The method as defined in claim 17, wherein the ion exchange membrane comprises a cation exchange membrane (CEM).

19. The method as defined in any one of claims 1 to 16, wherein the separator comprises a microporous polymer membrane.

20. The method as defined in any one of claims 1 to 19, wherein the separator is adapted to selectively allow passage of the metal ions.21 . The method as defined in any one of claims 1 to 20, further comprising maintaining the pH in the cathode chamber at between about 9 and about 13.

22. The method as defined in any one of claims 1 to 21 , further comprising maintaining the pH in the anode chamber at not greater than about 4.

23. The method as defined in any one of claims 1 to 22, further comprising suspending the metal-ion containing solid in a solvent to form the feedstock comprising the metal-ion containing solid before supplying the feedstock comprising the metal-ion containing solid to the anode chamber.

24. The method as defined in claim 23, wherein a concentration of the metal-ion containing solid in the solvent is in the range of from 0.01 to about 60 g / L.

25. The method as defined in any one of claims 1 to 24, wherein the metal-ion containing solid comprises silicate minerals.

26. The method as defined in any one of claims 1 to 25, wherein the reacting of the metal-ion containing solid with the hydrogen ions formed at the anode additionally yields a silicon-containing by-product.

27. The method as defined in claim 26, further comprising removing the silicon- containing by-product from the anode chamber.

28. The method as defined in claim 26 or 27, wherein the silicon-containing byproduct comprises the silica (SiC>2).

29. The method as defined in any one of claims 1 to 28, wherein the distance between the anode and the cathode is the thickness of the separator.

30. A carbon dioxide capture and storage system comprising: a source of a carbon dioxide feedstock; and an electrochemical reactor comprising: an anode exposed to an anode chamber, adapted to oxidize a first hydrogen-containing reactant to form hydrogen ions; a cathode exposed to a cathode chamber, adapted to reduce a second hydrogen-containing reactant to form hydroxide ions; a separator separating the anode chamber and the cathode chamber; an inlet at the cathode chamber fluidly connected to an outlet of the source of a carbon dioxide feedstock configured to supply the carbon dioxide feedstock from the source into the cathode chamber; an inlet at the anode chamber connected to receive a supply ofmetal-ion containing solids into the anode chamber, within which the metal-ion containing solids are caused to react with the hydrogen ions formed at the anode to produce metal ions and / or silica, the metal ions are permeated into the cathode chamber to react with the carbon dioxide feedstock to yield metal carbonate; and a power supply connected to apply a potential difference between the anode and the cathode.

31. The carbon dioxide capture and storage system as defined in claim 30, wherein the separator comprises an ion exchange membrane.

32. The carbon dioxide capture and storage system as defined claim 31 , wherein the ion exchange membrane comprises a cation exchange membrane (CEM).

33. The carbon dioxide capture and storage as defined in any one of claims 30 to 32, wherein the separator is adapted to selectively permeate divalent cations.

34. The carbon dioxide capture and storage system as defined in claim 30, wherein the separator comprises a microporous polymer membrane.

35. The carbon dioxide capture and storage system as defined in any one of claims 30 to 34, wherein the source of the carbon dioxide feedstock comprises a gas and / or an aqueous solution.

36. The carbon dioxide capture and storage system as defined in any one of claims 30 to 35, wherein the carbon dioxide feedstock comprises a capture solution comprising bicarbonate and / or carbonate ions.

37. The carbon dioxide capture and storage system as defined in any one of claims 30 to 36, wherein the carbon dioxide feedstock comprises air, flue gas and / or pure carbon dioxide gas.

38. The carbon dioxide capture and storage system as defined in any one of claims 30 to 37, wherein the source of the carbon dioxide feedstock comprises a contactor having a fluid inlet and a fluid outlet, the contactor configured to bring a gas comprising carbon dioxide, into contact with an aqueous solution provided at the fluid inlet, to absorb and chemically react gaseous carbon dioxide to form bicarbonate and / or carbonate in an aqueous solution for supply into the cathode chamber.

39. The carbon dioxide capture and storage system as defined in any one of claims 30 to 38, wherein one or both of the anode and / or the cathode comprise a free-standing layer of porous metal.

40. The carbon dioxide capture and storage system as defined in any one of claims 30 to 39, wherein one or both of the anode and / or the cathode comprise a free-standing layer of a Nickel foam.

41. The carbon dioxide capture and storage system as defined in any one of claims 30 to 38, wherein one or both of the anode and / or the cathode comprise a metal oxide composite.

42. The carbon dioxide capture and storage system as defined in claim 41 , wherein one or both of the anode and / or the cathode comprises iridium oxide (lrO2).

43. The carbon dioxide capture and storage system as defined in any one of claims 30 to 42, wherein a distance between the anode and cathode is a thickness of the separator.

44. A method of converting metal-ion containing solids comprising: applying an electrical potential between an anode and a cathode of an electrochemical cell, wherein the electrochemical cell comprises an anode chamber, a cathode chamber, and a separator separating the anode chamber and the cathode chamber; oxidizing, at the anode, a sulfur-containing species with a sulfur atom in a lower oxidation state contained in a first hydrogen-containing reactant to form a sulfur-containing species with a sulfur atom in a higher oxidation state and hydrogen ions; reducing a second hydrogen-containing reactant, at the cathode, to form hydroxide ions; supplying a feedstock comprising a metal-ion containing solid to the anode chamber; and reacting, at the anode chamber, the metal-ion containing solid with the hydrogen ions formed at the anode to yield metal ions and / or silica.

45. The method as defined in claim 44, further comprising: supplying a feedstock comprising metal ions to the cathode chamber;supplying a carbon dioxide feedstock to the cathode chamber; and reacting, in the cathode chamber, the hydroxide ions formed at the cathode with the carbon dioxide feedstock and the metal ions to yield metal carbonate.

46. The method as defined in claim 44 or 45, further comprising removing a solution from the anode chamber, the solution comprises the metal ions.

47. The method as defined in claim 46 , further comprising supplying the solution comprising the metal ions to the cathode chamber, causing the metal ions to react with the hydroxide ions formed at the cathode with the carbon dioxide feedstock to yield metal carbonate.

48. The method as defined in any one of claims 44 to 47, wherein the separator is adapted to selectively block passage of the metal ions.

49. The method as defined in claim 48, wherein the separator is adapted to selectively block passage of divalent cations.

50. The method as defined in claim 44, further comprising permeating the metal ions of the metal-ion containing solids from the anode chamber to the cathode chamber for reacting with the hydroxide ions formed at the cathode with the carbon dioxide feedstock to yield the metal carbonate.51 . The method as defined in any one of claims 44 to 50, wherein the separator comprises an ion exchange membrane.

52. The method as defined in claim 51 , wherein the ion exchange membrane comprises a cation exchange membrane (CEM).

53. The method as defined in any one of claims 44 to 50, wherein the separator comprises a microporous polymer membrane.

54. The method as defined in claim 53, wherein the separator is adapted to selectively allow passage of divalent cations.

55. The method as defined in any one of claims 44 to 54, further comprising maintaining the pH in the cathode chamber at between about 9 and about 13.

56. The method as defined in any one of claims 44 to 55, further comprising maintaining the pH in the anode chamber at not greater than about 4.

57. The method as defined in any one of claims 44 to 56, further comprising supplying a flow of an anolyte into the anode chamber.

58. The method as defined in any one of claims 44 to 57, further comprising supplying a flow of an anolyte comprising the sulfur-containing species with the sulfur atom in the lower oxidation state into the anode chamber.

59. The method as defined in any one of claims 44 to 58, wherein a concentration of the sullfur-containing species with the sulfur atom in the lower oxidation state in a solution is at least about 0.1 M.

60. The method as defined in any one of claims 44 to 59, wherein a concentration of the sullfur-containing species with the sulfur atom in the lower oxidation state in a solution is between 0.1 M and 2 M.

61. The method as defined in claim 60, wherein the solution comprises the anolyte.

62. The method as defined in any one of claims 57 to 61 , wherein the cations of the anolyte comprise an alkali metal ion and / or alkaline earth metal ion.

63. The method as defined in any one of claims 57 to 62, wherein the anolyte comprise one or more of NaCI, KCI, CaC and MgSCu.

64. The method as defined in any one of claims 57 to 63, wherein a concentration of the anolyte is up to about 14 M.

65. The method as defined in any one of claims 57 to 64, wherein a concentration of the anolyte is in the range of from about 0.1 M to about 1.0 M.

66. The method as defined in any one of claims 44 to 65, further comprising supplying a flow of a catholyte into the cathode chamber.

67. The method as defined in claim 66, wherein the cations and / or anions of the catholyte are divalent and / or monovalent.

68. The method as defined in claim 66 or 67, wherein the cations of the catholyte comprise an alkali metal ion and / or alkaline earth metal ion.

69. The method as defined in any one of claims 66 to 68, wherein a concentration of the catholyte is up to about 14 M.

70. The method as defined in any one of claims 66 to 69, wherein a concentration of the catholyte is in the range of from about 0.1 M to about 1.0 M.71 . The method as defined in any one of claims 44 to 70, wherein the second hydrogen-containing reactant comprises water.

72. The method as defined in any one of claims 44 to 71 , wherein the electrical potential of the electrochemical cell has a magnitude that does not exceed about 2 V.

73. The method as defined in any one of claims 44 to 72, wherein the electrical potential of the electrochemical cell has a magnitude that does not exceed about 1.4 V.

74. The method as defined in any one of claims 44 to 73, wherein the method comprises maintaining a current density of at least 25 mA cm-2.

75. The method as defined in any one of claims 44 to 74, wherein the method comprises maintaining a current density of at least 100 mA cm-2.

76. The method as defined in any one of claims 44 to 75, wherein the method comprises maintaining a current density between 100 mA cm-2and 500 mA cm-2.

77. The method as defined in any one of claims 44 to 76, wherein the oxidation state of the sulfur atom in the sulfur-containing species with a sulfur atom in the lower oxidation state is between -2 and +5.

78. The method as defined any one of claims 44 to 77, wherein the oxidation state of the sulfur atom in the sulfur-containing species with the sulfur atom in the higher oxidation state is between -1 and +6.

79. The method as defined in any one of claims 44 to 78, wherein the sulfur- containing species comprises one or more of elemental sulfur, sulfide ions, sulfite ions, and / or sulfur dioxide.

80. The method as defined in any one of claims 44 to 79, wherein the carbon dioxide feedstock comprises a gas and / or an aqueous solution.81 . The method as defined in any one of claims 44 to 80, wherein the carbon dioxide feedstock comprises a capture solution comprising bicarbonate and / or carbonate ions.

82. The method as defined in any one of claims 44 to 81 , wherein the carbon dioxide feedstock comprises air, flue gas and / or pure carbon dioxide gas.

83. The method as defined in any one of claims 44 to 82, further comprising suspending the metal-ion containing solid in a solvent to form the feedstockcomprising the metal-ion containing solid before supplying the feedstock comprising the metal-ion containing solid to the anode chamber.

84. The method as defined in any one of claims 44 to 83, wherein a concentration of the metal-ion containing solid in the solvent is in the range of from 0.01 to about 60 g / L.

85. The method as defined in any one of claims 44 to 84, wherein the metal-ion containing solids comprise silicate minerals.

86. The method as defined in any one of claims 44 to 85, wherein the reacting of the metal-ion containing solid with the hydrogen ions formed at the anode additionally yields a silicon-containing by-product.

87. The method as defined in claim 86, further comprising removing the silicon- containing by-product from the anode chamber.

88. The method as defined in claim 87, wherein the silicon-containing by-product comprises the silica (SiC>2).

89. The method as defined in any one of claims 44 to 88, wherein the distance between the anode and the cathode is the thickness of the separator.

90. A carbon dioxide capture and storage system comprising: a source of a carbon dioxide feedstock; a reservoir; an electrochemical reactor, the electrochemical reactor comprising: an anode exposed to an anode chamber, adapted to oxidize a sulfur- containing species with a sulfur atom in a lower oxidation state contained in a first hydrogen-containing reactant to form a sulfur-containing species with a sulfur atom in a higher oxidation state and hydrogen ions; a cathode exposed to a cathode chamber, adapted to reduce a second hydrogen-containing reactant to form hydroxide ions; a separator separating the anode chamber and the cathode chamber; a first inlet at the cathode chamber fluidly connected to an outlet of the source of the carbon dioxide feedstock configured to supply the carbon dioxide feedstock from the source into the cathode chamber; an inlet at the anode chamber connected to receive a supply ofmetal-ion containing solids into the anode chamber, within which the metal-ion containing solids are caused to react with the hydrogen ions formed at the anode to produce metal ions and / or silica; an outlet at the anode chamber fluidly connected to an inlet of the reservoir arranged for output of the metal ions formed at the anode chamber; a second inlet at the cathode chamber fluidly connected to an outlet of the reservoir arranged for input of the metal ions into the cathode chamber for reacting with the carbon dioxide feedstock to yield metal carbonate; and a power supply connected to apply a potential difference between the anode and the cathode.

91. The carbon dioxide capture and storage system as defined in claim 90, wherein the separator comprises an ion exchange membrane.

92. The carbon dioxide capture and storage system as defined in claim 91 , wherein the ion exchange membrane comprises a cation exchange membrane (CEM).

93. The carbon dioxide capture and storage system as defined in claim 90, wherein the separator comprises a microporous polymer membrane.

94. The carbon dioxide capture and storage system as defined in any one of claims 90 to 93, wherein the separator is adapted to selectively block passage of the metal ions.

95. The carbon dioxide capture and storage system as defined in any one of claims 90 to 94, wherein the separator is adapted to selectively block passage of the divalent cations.

96. The carbon dioxide capture and storage system as defined in any one of claims 90 to 95, wherein the source of the carbon dioxide feedstock comprises a gas and / or an aqueous solution.

97. The carbon dioxide capture and storage system as defined in any one of claims 90 to 96, wherein the carbon dioxide feedstock comprises a capture solution comprising bicarbonate and / or carbonate ions.

98. The carbon dioxide capture and storage system as defined in any one of claims 90 to 97, wherein the carbon dioxide feedstock comprises air, flue gas and / or pure carbon dioxide gas.

99. The carbon dioxide capture and storage system as defined in any one of claims 90 to 98, wherein the source of the carbon dioxide feedstock comprises a contactor having a fluid inlet and a fluid outlet, the contactor configured to bring a gas comprising carbon dioxide, into contact with an aqueous solution provided at the fluid inlet, to absorb and chemically react gaseous carbon dioxide to form bicarbonate and / or carbonate in an aqueous solution for supply into the cathode chamber.

100. The carbon dioxide capture and storage system as defined in any one of claims 90 to 99, wherein one or both of the anode and / or the cathode comprise a free-standing layer of porous metal.

101. The carbon dioxide capture and storage system as defined in any one of claims 90 to 100, wherein one or both of the anode and / or the cathode comprise a free-standing layer of a Nickel foam.

102. The carbon dioxide capture and storage system as defined in any one of claims 90 to 99, wherein one or both of the anode and / or the cathode comprise a free-standing layer of carbon.

103. The carbon dioxide capture and storage system as defined in claim 102, wherein a catalyst comprising platinum and / or carbon is deposited on the free-standing layer of carbon.

104. The carbon dioxide capture and storage system as defined in any one of claims 90 to 103, wherein a distance between the anode and cathode is a thickness of the separator.

105. The carbon dioxide capture and storage system as defined in any one of claims 90 to 104, further comprising a second inlet at the anode arranged to receive a supply of the sulfur-containing species with a sulfur atom in a lower oxidation state contained in a first hydrogen-containing reactant into the anode chamber.

106. A method of converting metal-ion containing solids comprising:applying an electrical potential between an anode and a cathode of an electrochemical cell, wherein the electrochemical cell comprises an anode chamber, a cathode chamber, a chemical chamber, a bipolar membrane separating the anode chamber and the chemical chamber, and a separator separating the chemical chamber and the cathode chamber; electrochemically dissociating at the bipolar membrane water into hydrogen ions and hydroxide ions; oxidizing an oxidation reactant, at the anode, to form an oxidation product; reducing a hydrogen-containing reactant, at the cathode, to form hydroxide ions; supplying a feedstock comprising metal-ion containing solids to the chemical chamber; reacting, in the chemical chamber, the metal-ion containing solids with the hydrogen ions formed at the bipolar membrane to yield metal ions and / or silica; permeating the metal ions through the separator from the chemical chamber to the cathode chamber; supplying a carbon dioxide feedstock to the cathode chamber; and reacting, in the cathode chamber, the hydroxide ions formed at the cathode with the carbon dioxide feedstock and the metal ions to yield metal carbonate.

107. The method as defined in claim 106, wherein the oxidation reactant comprises the hydroxide ions formed at the bipolar membrane.

108. The method as defined in claim 106 or 107, further comprising supplying a flow of catholyte into the cathode chamber.

109. The method as defined in any one of claims 106 to 108, further comprising supplying a flow of an amino acid and / or an amino acid salt contained in the catholyte into the cathode chamber.

110. The method as defined in claim 109, wherein a concentration of the amino acid and / or amino acid salt in the catholyte is up to about 1 M.

111. The method as defined in claim 109 or 110, wherein a molar percentage (mol %) of the amino acid salt in total amino acid species in the catholyte is up to about 100%.

112. The method as defined in any one of claims 106 to 111 , further comprising flowing a supply of chemolyte into the chemical chamber.

113. The method as defined in any one of claims 106 to 112, further comprising flowing a supply of the feedstock comprising metal-ion containing solids contained in the chemolyte into the chemical chamber.

114. The method as defined in claim 113, wherein the supply of the feedstock comprising the metal-ion containing solids contained in the chemolyte comprises an aqueous slurry of particles, and wherein a concentration of the aqueous slurry of particles is in the range of from about 1 g / L to about 100 g / L.

115. The method as defined any one of claims 112 to 114, wherein the chemolyte comprises a near-neutral pH aqueous solution.

116. The method as defined in any one of claims 112 to 115, wherein the chemolyte comprises a pH in the range of from about 6 to about 8.

117. The method as defined in any one of claims 112 to 116, wherein the chemolyte comprises a near-neutral to slightly basic pH aqueous solution.

118. The method as defined in any one of claims 112 to 117, wherein the chemolyte comprises a pH in the range of from about 7 to about 11 .

119. The method as defined in any one of claims 112 to 118, wherein the cations of the chemolyte are divalent and / or monovalent.

120. The method as defined in any one of claims 112 to 119, wherein the anions of the chemolyte are monovalent or divalent.121 . The method as defined in any one of claims 112 to 120, wherein a concentration of the chemolyte is up to about 14 M.

122. The method as defined in any one of any one of claims 106 to 121 , further comprising supplying a flow of an anolyte into the anode chamber.

123. The method as defined in any one of claims 106 to 122, wherein the oxidation reactant is contained in an anolyte.

124. The method as defined in claim 122 or 123, wherein the anolyte comprises a base.

125. The method as defined in any one of claims 122 to 124, wherein the cations of the anolyte comprise an alkali metal ion and / or an alkaline earth metal ion.

126. The method as defined in any one of claims 122 to 125, wherein a concentration of the anolyte is up to about 14 M.

127. The method as defined in any one of claims 106 to 126, wherein the hydrogen-containing reactant comprises water.

128. The method as defined in any one of claims 106 to 127, further comprising supplying a flow of catholyte into the cathode chamber.

129. The method as defined in any one of claims 106 to 128, wherein the supplying of the feedstock comprising carbon dioxide to the cathode chamber comprises bubbling the carbon dioxide into the catholyte in the cathode chamber.

130. The method as defined in claim 128 or 129, wherein the cations of the catholyte are monovalent.

131. The method as defined in any one of claims 128 to 130, wherein the anions of the catholyte are one or more of a halide anion, chlorate anion, perchlorate anion, bromate anion, perbromate anion, sulfate anion, nitrate anion, nitrite anion, organic carboxylic anion, acetate, propanoate, lactate, trihalide acetate anion, triflate anion, and bistriflimide anion.

132. The method as defined in any one of claims 126 to 131 , wherein a concentration of the catholyte is up to about 14 M.

133. The method as defined in any one of claims 106 to 132, further comprising maintaining the pH in the cathode chamber at between about 9 and about 13.

134. The method as defined in any one of claims 106 to 133, further comprising maintaining the pH in the chemical chamber at not greater than about 4.

135. The method as defined in any one of claims 106 to 134, wherein the separator comprises an ion exchange membrane.

136. The method as defined in claim 135, wherein the ion exchange membrane comprises a cation exchange membrane (CEM).

137. The method as defined in any one of claims 106 to 134 wherein the separator comprises a microporous polymer membrane.

138. The method as defined in any one of claims 106 to 137, wherein the separator is selectively permeable to divalent cations.

139. The method as defined in any one of claims 106 to 138, wherein the separator is adapted to be selectively permeable to the metal ions.

140. The method as defined in any one of claims 106 to 139, wherein the carbon dioxide feedstock comprises a gas and / or an aqueous solution.

141. The method as defined in any one of claims 106 to 140, wherein the carbon dioxide feedstock comprises a capture solution comprising bicarbonate and / or carbonate ions.

142. The method as defined in any one of claims 106 to 141 , wherein the carbon dioxide feedstock comprises air, flue gas and / or pure carbon dioxide gas.

143. The method as defined in any one of claims 106 to 142, wherein the metal-ion containing solids comprise silicate minerals.

144. The method as defined in any one of claims 106 to 143, wherein the reacting of the metal-ion containing solid with the hydrogen ions formed at the bipolar membrane additionally yields a silicon-containing by-product.

145. The method as defined in claim 144, further comprising removing the silicon-containing by-product from the chemical chamber.

146. The method as defined in claim 144 or 145, wherein the silicon- containing by-product comprises the silica (SiC>2).

147. A carbon dioxide capture and storage system comprising: a source of a carbon dioxide feedstock; and an electrochemical reactor comprising: an anode exposed to an anode chamber, adapted to oxidize an oxidation reactant to form an oxidation product; a cathode exposed to a cathode chamber, adapted to reduce a hydrogen-containing reactant to form hydroxide ions;a chemical chamber between the anode chamber and the cathode chamber; a bipolar membrane separating the anode chamber and the chemical chamber, the bipolar membrane being adapted to electrochemically dissociate water into hydrogen ions and hydroxide ions; a separator separating the chemical chamber and the cathode chamber; an inlet at the cathode chamber fluidly connected to an outlet of the source of the carbon dioxide feedstock configured to supply the carbon dioxide feedstock from the source into the cathode chamber; an inlet at the chemical chamber connected to receive a supply of metal-ion containing solids into the chemical chamber, within which the metal-ion containing solids are caused to react with the hydrogen ions formed at the bipolar membrane to produce metal ions and / or silica, the metal ions are permeated into the cathode chamber to react with the carbon dioxide feedstock to yield metal carbonate; and a power supply connected to apply a potential difference between the anode and the cathode.

148. The carbon dioxide capture and storage system as defined in claim147, wherein the separator comprises an ion exchange membrane.

149. The carbon dioxide capture and storage system as defined in claim148, wherein the ion exchange membrane comprises a cation exchange membrane (CEM).

150. The carbon dioxide capture and storage system as defined claim 147, wherein the separator comprises a microporous polymer membrane.

151. The carbon dioxide capture and storage system as defined in any one of claims 147 to 150, wherein the separator is adapted to be selectively permeable to divalent cations.

152. The carbon dioxide capture and storage system as defined in any one of claims 147 to 151 , wherein the separator is adapted to be selectively permeable to the metal ions.

153. The carbon dioxide capture and storage system as defined in any one of claims 147 to 152, wherein the source of the carbon dioxide feedstock comprises a gas and / or an aqueous solution.

154. The carbon dioxide capture and storage system as defined in claim 153, wherein the carbon dioxide feedstock comprises a capture solution comprising bicarbonate and / or carbonate ions.

155. The carbon dioxide capture and storage system as defined claim 153 or 154 wherein the carbon dioxide feedstock comprises air, flue gas and / or pure carbon dioxide gas.

156. The carbon dioxide capture and storage system as defined in any one of claims 147 to 155, wherein the source of the carbon dioxide feedstock comprises a contactor having a fluid inlet and a fluid outlet, the contactor configured to bring a gas comprising carbon dioxide, into contact with an aqueous solution provided at the fluid inlet, to absorb and chemically react gaseous carbon dioxide to form bicarbonate and / or carbonate in an aqueous solution for supply into the cathode chamber.

157. The carbon dioxide capture and storage system as defined in any one of claims 147 to 156, wherein one or both of the anode and / or the cathode comprise a free-standing layer of porous metal.

158. The carbon dioxide capture and storage system as defined in any one of claims 147 to 157, wherein one or both of the anode and / or the cathode comprise a free-standing layer of a Nickel foam.

159. A method of producing a sulfur-containing species with a sulfur atom in a higher oxidation state comprising: applying an electrical potential between an anode and a cathode of an electrochemical cell, wherein the electrochemical cell comprises an anode chamber, a cathode chamber, and a separator separating the anode chamber and the cathode chamber; oxidizing, at the anode, a sulfur-containing species with a sulfur atom in a lower oxidation state contained in a first hydrogen-containing reactant to form a sulfur-containing species with the sulfur atom in a higher oxidation state and hydrogen ions; andreducing a reduction reactant, at the cathode, to form a reduction product.

160. The method as defined in claim 159, wherein the reduction reactant comprises a hydrogen-containing reactant and the reduction product comprises hydroxide ions.

161. The method as defined in claim 159 or 160, wherein the electrical potential of the electrochemical cell has a magnitude that does not exceed about 2 V.

162. The method as defined in any one of claims 159 to 161 , wherein the electrical potential of the electrochemical cell has a magnitude that does not exceed about 1 .4 V.

163. The method as defined in any one of claims 159 to 162, wherein the method comprises maintaining a current density of at least 25 mA cm-2.

164. The method as defined in any one of claims 159 to 163, wherein the method comprises maintaining a current density of at least 100 mA cm-2.

165. The method as defined in any one of claims 159 to 164, wherein the method comprises maintaining a current density between 100 mA cm-2and 500 mA cm-2.

166. The method as defined in any one of claims 159 to 165, wherein the oxidation state of the sulfur atom in the sulfur-containing species with the sulfur atom in the lower oxidation state is between -2 and +5.

167. The method as defined in any one of claims 159 to 166, wherein the oxidation state of the sulfur atom in the sulfur-containing species with the sulfur atom in the higher oxidation state is between -1 and +6.

168. The method as defined in any one of claims 159 to 167, wherein the sulfur-containing species comprises one or more of elemental sulfur, sulfide ions, sulfite ions, and / or sulfur dioxide.

169. The method as defined in any one of claims 159 to 168, wherein the sulfur-containing species with the sulfur atom in the higher oxidation state comprise sulfuric acid.

170. The method as defined in any one of claims 159 to 169, further comprising supplying a flow of an anolyte into the anode chamber.

171. The method as defined in any one of claims 159 to 170, further comprising supplying a flow of an anolyte comprising the sulfur-containing species with the sulfur atom in the lower oxidation state into the anode chamber.

172. The method as defined in any one of claims 159 to 171 , wherein a concentration of the sullfur-containing species with the sulfur atom in the lower oxidation state in the anolyte is at least about 0.1 M.

173. The method as defined in any one of claims 159 to 172, wherein a concentration of the sullfur-containing species with the sulfur atom in the lower oxidation state in the anolyte is between 0.1 M and 2 M.

174. The method as defined in any one of claims 170 to 173, wherein the cations of the anolyte comprise an alkali metal ion and / or alkaline earth metal ion.

175. The method as defined in any one of claims 170 to 174, wherein the anolyte comprise one or more of NaCI, KCI, CaC and MgSCu.

176. The method as defined in any one of claims 170 to 175, wherein a concentration of the anolyte is up to about 14 M.

177. The method as defined in any one of claims 170 to 176, wherein a concentration of the anolyte is in the range of from about 0.1 M to about 1.0 M.

178. The method as defined in any one of claims 159 to 177, further comprising supplying a flow of a catholyte into the cathode chamber.

179. The method as defined in claim 178, wherein the catholyte comprises a near-neutral pH aqueous solution.

180. The method as defined in claim 178 or 179, wherein the catholyte comprises a pH in the range of from about 6 to about 8.

181. The method as defined in any one of claims 178 to 180, wherein the cations and / or anions of the catholyte are divalent and / or monovalent.

182. The method as defined in any one of claims 178 to 181 , wherein the cations of the catholyte comprise an alkali metal ion and / or alkaline earth metal ion.

183. The method as defined in any one of claims 178 to 182, wherein a concentration of the catholyte is up to about 14 M.

184. The method as defined in any one of claims 178 to 183, wherein a concentration of the catholyte is in the range of from about 0.1 M to about 1 .0 M.

185. The method as defined in any one of claims 159 to 184, wherein the distance between the anode and the cathode is the thickness of the separator.

186. The method as defined in any one of claims 159 to 185, wherein the separator comprises an ion exchange membrane.

187. The method as defined in claim 186, wherein the separator comprises a cation exchange membrane.

188. A method of converting metal-ion containing solids, the method comprising: applying an electrical potential between an anode and a cathode of an electrochemical cell, wherein the electrochemical cell comprises an anode chamber, a cathode chamber, and a separator separating the anode chamber and the cathode chamber; oxidizing an oxidation reactant, at the anode, to form an oxidation product; reducing a reduction reactant, at the cathode, to form hydroxide ions; flowing electrolyte from the electrochemical cell to a solid-liquid extractor comprising the metal-ion containing solids; extracting, in the solid-liquid extractor, metal ions from the metal-ion containing solids, thereby forming a metal-ion-enriched electrolyte comprising the metal ions; flowing the metal-ion-enriched electrolyte from the solid-liquid extractor to the electrochemical cell; permeating the metal ions in the metal-ion-enriched electrolyte to the cathode chamber; flowing the metal ions and / or the hydroxide ions formed at the cathode out of the cathode chamber.

189. The method as defined in claim 188, wherein the flowing of the metal ions and / or hydroxide ions out of the cathode chamber comprises flowing amixture comprising the metal ions, hydroxide ions and an electrolyte out of the cathode chamber.

190. The method as defined in claim 188 or 189, further comprising: supplying the mixture to a carbon capture and storage unit; supplying a carbon dioxide feedstock into the carbon capture and storage unit; and reacting the metal ions, hydroxide ions and the carbon dioxide feedstock to yield metal carbonates.

191. The method as defined in claim 190, further comprising separating, in the carbon capture and storage unit the metal carbonates from the mixture comprising the electrolyte.

192. The method as defined in claim 191 , further comprising recycling the separated electrolyte to the electrochemical cell.

193. The method as defined in any one of claims 188 to 192, wherein a distance between the anode and cathode is the thickness of the separator.

194. The method as defined in any one of claims 188 to 193, wherein the flowing of the electrolyte from the electrochemical cell to the solid-liquid extractor comprises flowing the electrolyte from the anode chamber to the solid-liquid extractor.

195. The method as defined in claim 188, wherein the electrochemical cell additionally comprises a chemical chamber and a bipolar membrane separating the anode chamber and the chemical chamber, and wherein the separator is positioned between the chemical chamber and the cathode chamber, wherein the method further comprises electrochemically dissociating water, within the bipolar membrane, into hydrogen ions and hydroxide ions.

196. The method as defined in claim 195, wherein the flowing of electrolyte from the electrochemical cell to the solid-liquid extractor comprises flowing the electrolyte from the chemical chamber to the solid-liquid extractor.

197. The method as defined in claim 195 or 196, wherein the step of recycling of the separated electrolyte to the electrochemical cell comprises supplying the separated electrolyte to the cathode chamber.

198. The method as defined in any one of claims 188 to 197, further comprising flowing a supply of an anolyte into the anode chamber.

199. The method as defined in any one of claims 188 to 198, wherein the oxidation reactant comprises a hydrogen-containing reactant.

200. The method as defined in claim 199, wherein the hydrogen-containing reactant comprises water.201 . The method as defined in any one of claims 188 to 200, wherein the oxidation product comprises hydrogen ions.

202. The method as defined in claim 201 , wherein the oxidation reactant comprises a base.

203. The method as defined in any one of claims 198 to 202, wherein the anolyte comprises the oxidation reactant.

204. The method as defined in any one of claims 188 to 203, wherein the reduction reactant comprises a hydrogen-containing reactant.

205. The method as defined in claim 204, wherein the hydrogen-containing reactant comprises water.

206. The method as defined in any one of claims 188 to 205, further comprising flowing a supply of the catholyte into the cathode chamber.

207. The method as defined in any one of claims 188 to 206, further comprising flowing a supply of chemolyte into the chemical chamber.

208. The method as defined in claim 206 or 207, wherein the anolyte, catholyte and / or chemolyte is derived from a pH-neutral aqueous solution.

209. The method as defined in any one of claims 206 to 208, wherein the anolyte, catholyte and / or chemolyte comprise a pH in the range of from about 6 to about 8.

210. The method as defined in any one of claims 206 to 209, wherein the anions and / or cations of the anolyte, catholyte and / or chemolyte are monovalent.

211. The method as defined in any one of claims 206 to 210, wherein a concentration of the anolyte, catholyte and / or chemolyte is in the range of from about 0.1 M to about 5 M.

212. The method as defined in any one of claims 188 to 211 , further comprising maintaining the pH in the cathode chamber at not less than about 9 during electrolysis.

213. The method as defined in any one of claims 188 to 212, further comprising maintaining the pH in the cathode chamber between about 10 to about 14 during electrolysis.

214. The method as defined in any one of claims 188 to 213, wherein the pH of the electrolyte being supplied to the liquid-solid extractor is from about 0.2 to about 3.

215. The method as defined in any one of claims 188 to 214, wherein the separator comprises an ion exchange membrane.

216. The method as defined in claim 215, wherein the ion exchange membrane comprises a cation exchange membrane (CEM).

217. The method as defined in any one of claims 188 to 214, wherein the separator comprises a microporous polymer membrane.

218. The method as defined in any one of claims 188 to 217, wherein the separator is selectively permeable to divalent cations.

219. The method as defined in any one of claims 188 to 218, wherein the carbon dioxide feedstock comprises a gas and / or an aqueous solution.

220. The method as defined in any one of claims 188 to 219, wherein the carbon dioxide feedstock comprises a capture solution comprising bicarbonate and / or carbonate ions.

221. The method as defined in any one of claims 188 to 220, wherein the carbon dioxide feedstock comprises air, flue gas and / or pure carbon dioxide gas.

222. The method as defined in any one of claims 188 to 221 , wherein the metal-ion containing solids comprise a silicate containing mineral.

223. The method as defined in any one of claims 188 to 222, further comprising collecting silica from the solid-liquid extractor in the extracting step.

224. The method as defined in any one of claims 188 to 223, further comprising flowing the electrolyte into a first gas-liquid separator configured toseparate one or more gasses from the electrolyte, before flowing the electrolyte into the solid-liquid extractor from the electrochemical cell.

225. The method as defined in claim 224, further comprising flowing the separated electrolyte into a second gas-liquid separator configured to separate one or more gasses from the separator electrolyte, before recycling the separated electrolyte from the carbon capture and storage unit to the electrochemical cell.

226. A system of converting metal-ion containing solids, the system comprising: an electrochemical cell comprising: an anode exposed in an anode chamber, adapted to oxidize an oxidation reactant to form an oxidation product; a cathode exposed in a cathode chamber, adapted to reduce a reduction reactant to form hydroxide ions; and a separator separating the anode chamber and the cathode chamber; a solid-liquid extractor, adapted to extract metal ions from the metal-ion containing solids, thereby forming a metal-ion-enriched electrolyte comprising the metal ions, the solid-liquid extractor comprising: an extractor inlet flowingly connected to a first outlet of the electrochemical cell, for flowing an electrolyte from the electrochemical cell to the solid-liquid extractor; an extractor outlet flowingly connected to a cell inlet, for flowing the metal-ion-enriched electrolyte into the electrochemical cell so that the metal ions in the metal-ion-enriched electrolyte permeate through the separator to the cathode chamber; and a second outlet of the electrochemical cell for flowing the metal ions and / or hydroxide ions formed at the cathode out of the cathode chamber.

227. The system as defined in claim 226, further comprising: a carbon capture and storage unit, the carbon capture storage unit comprising; an inlet fluidly connected to the second outlet of the electrochemical cell for receiving a flow of the metal ions and / or hydroxide ions from the cathode chamber;an outlet fluidly connected to a second cell inlet for flowing a supply of separated electrolyte into the electrochemical cell; and a source of carbon dioxide feedstock comprising an inlet flowingly connected to an inlet of the carbon capture and storage unit, for flowing a supply of carbon dioxide feedstock into the carbon capture and storage unit for bringing the metal ions, the hydroxide ions and the carbon dioxide feedstock into contact in the carbon capture and storage unit for reaction to yield metal carbonates.

228. The system as defined in claim 226 or 227, wherein the separator is adapted to allow passage of divalent ions.

229. The system as defined in any one of claims 226 to 228, wherein the separator comprises an ion exchange membrane.

230. The system as defined in claim 229, wherein the ion exchange membrane comprises a cation exchange membrane (CEM).231 . The system as defined in any one of claims 226 to 230, wherein the first outlet of the electrochemical cell is arranged for flowing electrolyte out of the anode chamber.

232. The system as defined in any one of claims 226 to 231 , wherein the first inlet is arranged to introduce the separated electrolyte into the cathode chamber.

233. The system as defined in any one of claims 226 to 232, wherein a distance between the anode and cathode is the thickness of the separator.

234. The system as defined in any one of claims 226 to 230, further comprising: a chemical chamber between the anode chamber and the cathode chamber; and a bipolar membrane separating the chemical chamber and the anode chamber, the bipolar membrane being adapted to electrochemically dissociate water into hydrogen ions and hydroxide ions, and wherein the separator separates the chemical chamber and the cathode chamber.

235. The system as defined in claim 234, wherein the first outlet of the electrochemical cell is arranged for flowing electrolyte out of the chemical reaction chamber.

236. The system as defined in any one of claims 226 to 235, further comprising a reservoir connected to supply a flow of anolyte into the anode chamber.

237. The system as defined in claim 236, wherein the anolyte comprises the oxidation reactant.

238. The system as defined in claim 236 or 237, wherein the anolyte comprises a hydrogen-containing reactant.

239. The system as defined in any one of claims 236 to 238, wherein the anolyte comprises a base.

240. The system as defined in any one of claims 236 to 239, further comprising a reservoir connected to supply a flow of catholyte into the cathode chamber.241 . The system as defined in any one of claims 234 to 240, further comprising a reservoir connected to supply a flow of chemolyte into the chemical reaction chamber.

242. The system as defined in 241 , wherein the anolyte, catholyte and / or chemolyte comprises a pH-neutral aqueous solution.

243. The system as defined in claim 241 or 242, wherein the anolyte, catholyte and / or chemolyte comprises a pH in the range of from about 6 to about 8.

244. The system as defined in any one of claims 241 to 243, wherein the anolyte, catholyte and / or chemolyte are monovalent.

245. The system as defined in any one of claims 241 to 244, wherein a concentration of the the anolyte, catholyte and / or chemolyte is in the range of from about 0.1 M to about 5 M.

246. The system as defined in any one of claims 226 to 245, wherein the reduction reactant comprises a hydrogen-containing reactant.

247. The system as defined in claim 246, wherein the hydrogen-containing reactant comprises water.

248. The system as defined in any one of claims 226 to 247, further comprising a first gas-liquid separator arranged between the first outlet of the electrochemical cell and the extractor inlet, the first gas-liquid separator being adapted to remove one or more gasses from the electrolyte before flowing into the solid-liquid extractor.

249. The system as defined in claim 248, further comprising a second gasliquid separator arranged between the filtration outlet and the first inlet of the electrochemical cell, the second gas-liquid separator being adapted to remove one or more gasses from the separated electrolyte before being recycled into the electrochemical cell.

250. The system as defined in any one of claims 226 to 249, further comprising a solid collector connected to receive a supply of the silica discharged from the solid-liquid extractor.251 . The system as defined in any one of claims 226 to 250, wherein the metal-ion containing solids comprise a silicate containing mineral.